Computer controlled surgical rotary tool

ABSTRACT

A rotary tool includes a tool body and a powered rotary cutting tooltip that is oriented and positioned relative to the tool body by a plurality of processor-controlled actuators that provide degrees of freedom. The processor uses a surgical tracking system to identify the pose of the tool body and the tooltip relative to a patient&#39;s anatomy and controls the actuators to maintain the tooltip within a predetermined cutting plan to compensate for deviation of a surgeon&#39;s hand or a robotic arm controlling the tool body during a cutting operation.

CLAIM OF PRIORITY

This application claims the benefit of priority to U.S. ProvisionalApplication No. 62/863,039, titled “Computer Controlled Surgical RotaryTool,” filed Jun. 18, 2019, which is incorporated herein by reference inits entirety.

TECHNICAL FIELD

The present disclosure relates generally to methods, systems, andapparatuses related to surgical rotary tool for resection bone incooperation with a computer-assisted surgical system that includesvarious hardware and software components that work together to enhancesurgical workflows and outcomes. More particularly, the presentdisclosure relates to a surgical rotary tool configured to be maintainedwith respect to a virtual cutting plane under the control of thecomputer-assisted surgical system. The disclosed techniques may beapplied to, for example, shoulder, hip, and knee surgical procedures, aswell as other surgical interventions such as arthroscopic procedures,spinal procedures, maxillofacial procedures, rotator cuff procedures,ligament repair and replacement procedures.

BACKGROUND

Conventional surgical operations have recently been enhanced through theuse of robotic assistance. Robotic assistance can take on variousdegrees of enhancement to the traditional surgical process. Roboticenhancements can fully automate surgery or provide tracking and guidanceto a surgeon beyond what may have traditionally been available. One typeof system used to robotically enhance surgery is the NAVIO surgicalsystem available from Smith and Nephew, Inc. NAVIO is a registered markof Blue Belt Technologies, Inc., a wholly-owned subsidiary of Smith &Nephew.

Resection of bone for total knee replacement is commonly done using anoscillating saw and a cutting guide or jig. Postoperative function,pain, rehabilitation, and satisfaction can all be influenced by theplacement of the implant. Robot assisted total knee arthroplasty (suchas can be performed using the NAVIO system) seeks to improve accuracyand repeatability of implant placement. A disadvantage of some roboticsurgical systems is the somewhat lengthy time required to resect thevolume of bone necessary for a total knee replacement using thevolumetric resection methods, such as a rotary burr.

In order to overcome the limitations of resection rates achievable witha burr, some systems utilize a hybrid approach where features of limitedsize are burred in specific/pre-planned locations using the robotichandpiece. Thereafter, a special cutting jig interfaces with the burredfeatures in the bone which places the jigs into the correctposition/orientation to resect bone using the traditional oscillatingsaw, allowing sections of bone to be cut off rather than ground down.

While this approach may be quicker than burring alone, it can haveseveral limitations. For example, the features burred for cutting guidesare “post holes” which are cumbersome for surgeons to create. Placementof cutting jigs into burred features can introduce additional error.Cutting with a saw can introduce yet more error. Some robotic systemsutilize a robotic arm to directly constrain the saw to a resectionplane. This can overcomes limitations of a system that mounts cuttingguides using burred post holes. However, the complexity of the roboticarm can greatly increase cost.

The exemplary NAVIO surgical system assists surgeons by using opticaltracking of tools in the surgical theater and tracking of patientanatomy relative to the tools. This tracking is typically performed byapplying mechanical fiducial marks to the patient's anatomy (e.g.,temporarily affixing fiducial markers to a patient's bone structureduring arthroplasty and mounting fiducial markers to handpieces fortools). By using fiducial markers, objects within the surgical theatrecan be optically tracked reliably and precisely. Once the objects in thesurgical theatre are registered spatially with one another by theoptical tracking system, any future movement of those objects can betracked, and their motion can be captured and calculated via imageprocessing and geometric modeling.

For example, once fiducial markers have been affixed to a patient'sbones and have been registered with the system and a tool/handpiece alsohas been registered with the system, a surgeon can use thattool/handpiece to impinge the bone and register, via that impingement,the location of the salient features of the patient's bone structure.For example, during a knee replacement or corrective surgery, fiducialmarkers can be affixed to the femur and tibia. Using a probe with a tipat a predetermined location and orientation relative to fiducial markersattached to the probe, a surgeon can touch the tip of the probe tospecific features on a tibial plateau and femoral condyles or to otherimportant features for the surgical procedure. By tracking the locationand orientation of the tibia and femur, via optical tracking of thefiducial markers, and by tracking the position and location of the probe(at the time of impingement of the bone to register those features ofthe tibia and femur), a three-dimensional model of the surgical theatrecan be created via the robotic optical tracking system. Once thelocation of important features of the patient's bone structure have beenidentified and registered relative to fiducial markers, all futureinteraction with those bone features can be determined based on thelocation and the orientation of the tool relative to the fiducialmarkers on the bones.

SUMMARY

This summary is provided to comply with 37 C.F.R. § 1.73. It issubmitted with the understanding that it will not be used to interpretor limit the scope or meaning of the present disclosure.

A system for resecting a bone of a patient is provided. The systemcomprises a rotary tool having a tool body, a tracking array affixed tothe tool body, the tracking array comprising three or more fiducialmarkers, a powered rotary cutting tip comprising a longitudinal axis,wherein the rotary cutting tip is affixed to the tool body and rotatableabout the longitudinal axis by a motor to resect the bone, first andsecond linear actuators configured to adjust one or more of a verticalposition and a pitch position of the rotary cutting tip with respect tothe tool body, and a tool rest extending from the tool body configuredto maintain contact with the bone as the tool body is moved to resectthe bone; a surgical tracking device configured to identify a positionof each of the one or more fiducial markers with respect to the bone;and a processor configured to receive a surgical plan comprising atleast one virtual cutting plane on the bone, receive a position of thetracking array from the surgical tracking device, determine, based onthe position of the tracking array, a real-time pose of the cutting tipwith respect to the at least one virtual cutting plane, and control thefirst and second linear actuators, based on the real-time pose, toadjust one or more of the vertical position and the pitch position ofthe rotary cutting tip with respect to the tool body in order tomaintain the rotary cutting tip on the at least one virtual cuttingplane.

According to some embodiments, the rotary cutting tip has a fixedhorizontal position and a fixed axial position with respect to the toolbody.

According to some embodiments, the rotary cutting tip has a fixed yawposition with respect to the tool body.

According to some embodiments, the processor is configured to preventthe rotary cutting tip from cutting across the at least one virtualcutting plane.

According to some embodiments, the at least one virtual cutting planecomprises a vertical cutting plane and a horizontal cutting plane.According to additional embodiments, the processor is further configuredto maintain the longitudinal axis of the rotary cutting tip on thevertical cutting plane when a movement axis of the first and secondlinear actuators is substantially orthogonal to the vertical cuttingplane; and maintain the longitudinal axis of the rotary cutting tip onthe horizontal cutting plane when the movement axis of the first andsecond linear actuators is substantially orthogonal to the horizontalcutting plane. According to additional embodiments, the tool rest isfurther configured to pivot about a fixed point on a contact surfacewith the bone during movement of the rotary cutting tip along thevertical cutting plane; and move along the contact surface of the boneduring movement of the rotary cutting tip along the horizontal cuttingplane.

According to some embodiments, the processor is further configured tocontrol a speed of rotation of the rotary cutting tip about thelongitudinal axis to resect the bone. According to additionalembodiments, the processor is further configured to stop rotation of therotary cutting tip when the rotary cutting tip intersects the at leastone virtual cutting plane. According to additional embodiments, theprocessor is further configured to stop rotation of the rotary cuttingtip when the rotary cutting tip is moved outside of a prescribed cuttingarea.

According to some embodiments, each of the first and second linearactuators comprises one or more of a linear motor, a piezoelectricmotor, a pneumatic motor, a hydraulic motor, and a gear motor.

According to some embodiments, the tool rest is rotatable with respectto the tool body.

According to some embodiments, the processor is further configured tocontrol a position of a robotic arm to which the rotary tool is affixed.

A rotary tool for resecting a bone of a patient is provided. The rotarycutting tool comprises a tool body; a tracking array affixed to a toolbody, the tracking array comprising one or more fiducial markersconfigured to be tracked by a surgical tracking system; a powered rotarycutting tip comprising a longitudinal axis, wherein the rotary cuttingtip is affixed to the tool body and rotatable about the longitudinalaxis by a motor to resect the bone of the patient; first and secondlinear actuators configured to be controlled by a processor to adjustone or more of a vertical position and a pitch position of the rotarycutting tip with respect to the tool body to maintain the rotary cuttingtip on the at least one virtual cutting plane; and a tool rest extendingfrom the tool body configured to maintain contact with the bone as thetool body is moved to resect the bone.

According to some embodiments, the rotary cutting tip has a fixedhorizontal position and a fixed axial position with respect to the toolbody.

According to some embodiments, the rotary cutting tip has a fixed yawposition with respect to the tool body.

According to some embodiments, each of the first and second linearactuators comprises one or more of a linear motor, a piezoelectricmotor, a pneumatic motor, a hydraulic motor, and a gear motor.

According to some embodiments, the tool rest is rotatable with respectto the tool body.

According to some embodiments, the rotary tool is configured to beaffixed to a robotic arm, wherein the processor is further configured tocontrol a position of the robotic arm.

According to some embodiments, the tool rest is further configured topivot about a fixed point on a contact surface with the bone duringmovement of the rotary cutting tip along a vertical cutting plane; andmove along the contact surface of the bone during movement of the rotarycutting tip along a horizontal cutting plane.

BRIEF DESCRIPTION OF THE FIGURES

The accompanying drawings, which are incorporated in and form a part ofthe specification, illustrate the embodiments of the invention andtogether with the written description serve to explain the principles,characteristics, and features of the invention. In the drawings:

FIG. 1 depicts an operating theatre including an illustrativecomputer-assisted surgical system (CASS) in accordance with anembodiment.

FIG. 2 depicts an example of an electromagnetic sensor device accordingto some embodiments.

FIG. 3A depicts an alternative example of an electromagnetic sensordevice, with three perpendicular coils, according to some embodiments.

FIG. 3B depicts an alternative example of an electromagnetic sensordevice, with two nonparallel, affixed coils, according to someembodiments.

FIG. 3C depicts an alternative example of an electromagnetic sensordevice, with two nonparallel, separate coils, according to someembodiments.

FIG. 4 depicts an example of electromagnetic sensor devices and apatient bone according to some embodiments

FIG. 5A depicts illustrative control instructions that a surgicalcomputer provides to other components of a CASS in accordance with anembodiment.

FIG. 5B depicts illustrative control instructions that components of aCASS provide to a surgical computer in accordance with an embodiment.

FIG. 5C depicts an illustrative implementation in which a surgicalcomputer is connected to a surgical data server via a network inaccordance with an embodiment.

FIG. 6 depicts an operative patient care system and illustrative datasources in accordance with an embodiment.

FIG. 7A depicts an illustrative flow diagram for determining apre-operative surgical plan in accordance with an embodiment.

FIG. 7B depicts an illustrative flow diagram for determining an episodeof care including pre-operative, intraoperative, and post-operativeactions in accordance with an embodiment.

FIG. 7C depicts illustrative graphical user interfaces including imagesdepicting an implant placement in accordance with an embodiment.

FIG. 8 is a side view of a cutting tool resecting a portion of a patienttibia, in accordance with some embodiments;

FIG. 9 is a pair of lateral cutaway views of a cutting tool compensatingfor tool body movement during a cutting operation on a patient bone, inaccordance with some embodiments;

FIG. 10 is a pair of side views of a cutting tool performing a verticalcutting operation on a patient bone, in accordance with someembodiments;

FIG. 11 is a pair of side views of a cutting tool performing ahorizontal cutting operation on a patient bone, in accordance with someembodiments;

FIG. 12 is a system diagram of a surgical system utilizing a cuttingtool, in accordance with some embodiments;

FIG. 13 is a flowchart of the exemplary operation of a surgical systemutilizing a cutting tool, in accordance with some embodiments; and

FIG. 14 depicts a block diagram of an example environment for operatinga system for navigation and control of a computer-aided surgicalnavigation system according to an illustrative embodiment.

DETAILED DESCRIPTION

This disclosure is not limited to the particular systems, devices andmethods described, as these may vary. The terminology used in thedescription is for the purpose of describing the particular versions orembodiments only, and is not intended to limit the scope.

As used in this document, the singular forms “a,” “an,” and “the”include plural references unless the context clearly dictates otherwise.Unless defined otherwise, all technical and scientific terms used hereinhave the same meanings as commonly understood by one of ordinary skillin the art. Nothing in this disclosure is to be construed as anadmission that the embodiments described in this disclosure are notentitled to antedate such disclosure by virtue of prior invention. Asused in this document, the term “comprising” means “including, but notlimited to.”

Definitions

For the purposes of this disclosure, the term “implant” is used to referto a prosthetic device or structure manufactured to replace or enhance abiological structure. For example, in a total hip replacement procedurea prosthetic acetabular cup (implant) is used to replace or enhance apatients worn or damaged acetabulum. While the term “implant” isgenerally considered to denote a man-made structure (as contrasted witha transplant), for the purposes of this specification an implant caninclude a biological tissue or material transplanted to replace orenhance a biological structure.

For the purposes of this disclosure, the term “real-time” is used torefer to calculations or operations performed on-the-fly as events occuror input is received by the operable system. However, the use of theterm “real-time” is not intended to preclude operations that cause somelatency between input and response, so long as the latency is anunintended consequence induced by the performance characteristics of themachine.

Although much of this disclosure refers to surgeons or other medicalprofessionals by specific job title or role, nothing in this disclosureis intended to be limited to a specific job title or function. Surgeonsor medical professionals can include any doctor, nurse, medicalprofessional, or technician. Any of these terms or job titles can beused interchangeably with the user of the systems disclosed hereinunless otherwise explicitly demarcated. For example, a reference to asurgeon could also apply, in some embodiments to a technician or nurse.

CASS Ecosystem Overview

FIG. 1 provides an illustration of an example computer-assisted surgicalsystem (CASS) 100, according to some embodiments. As described infurther detail in the sections that follow, the CASS uses computers,robotics, and imaging technology to aid surgeons in performingorthopedic surgery procedures such as total knee arthroplasty (TKA) ortotal hip arthroplasty (THA). For example, surgical navigation systemscan aid surgeons in locating patient anatomical structures, guidingsurgical instruments, and implanting medical devices with a high degreeof accuracy. Surgical navigation systems such as the CASS 100 oftenemploy various forms of computing technology to perform a wide varietyof standard and minimally invasive surgical procedures and techniques.Moreover, these systems allow surgeons to more accurately plan, trackand navigate the placement of instruments and implants relative to thebody of a patient, as well as conduct pre-operative and intra-operativebody imaging.

An Effector Platform 105 positions surgical tools relative to a patientduring surgery. The exact components of the Effector Platform 105 willvary, depending on the embodiment employed. For example, for a kneesurgery, the Effector Platform 105 may include an End Effector 105B thatholds surgical tools or instruments during their use. The End Effector105B may be a handheld device or instrument used by the surgeon (e.g., aNAVIO® hand piece or a cutting guide or jig) or, alternatively, the EndEffector 105B can include a device or instrument held or positioned by aRobotic Arm 105A. While one Robotic Arm 105A is illustrated in FIG. 1,in some embodiments there may be multiple devices. As examples, theremay be one Robotic Arm 105A on each side of an operating table T or twodevices on one side of the table T. The Robotic Arm 105A may be mounteddirectly to the table T, be located next to the table T on a floorplatform (not shown), mounted on a floor-to-ceiling pole, or mounted ona wall or ceiling of an operating room. The floor platform may be fixedor moveable. In one particular embodiment, the robotic arm 105A ismounted on a floor-to-ceiling pole located between the patient's legs orfeet. In some embodiments, the End Effector 105B may include a sutureholder or a stapler to assist in closing wounds. Further, in the case oftwo robotic arms 105A, the surgical computer 150 can drive the roboticarms 105A to work together to suture the wound at closure.Alternatively, the surgical computer 150 can drive one or more roboticarms 105A to staple the wound at closure.

The Effector Platform 105 can include a Limb Positioner 105C forpositioning the patient's limbs during surgery. One example of a LimbPositioner 105C is the SMITH AND NEPHEW SPIDER2 system. The LimbPositioner 105C may be operated manually by the surgeon or alternativelychange limb positions based on instructions received from the SurgicalComputer 150 (described below). While one Limb Positioner 105C isillustrated in FIG. 1, in some embodiments there may be multipledevices. As examples, there may be one Limb Positioner 105C on each sideof the operating table T or two devices on one side of the table T. TheLimb Positioner 105C may be mounted directly to the table T, be locatednext to the table T on a floor platform (not shown), mounted on a pole,or mounted on a wall or ceiling of an operating room. In someembodiments, the Limb Positioner 105C can be used in non-conventionalways, such as a retractor or specific bone holder. The Limb Positioner105C may include, as examples, an ankle boot, a soft tissue clamp, abone clamp, or a soft-tissue retractor spoon, such as a hooked, curved,or angled blade. In some embodiments, the Limb Positioner 105C mayinclude a suture holder to assist in closing wounds.

The Effector Platform 105 may include tools, such as a screwdriver,light or laser, to indicate an axis or plane, bubble level, pin driver,pin puller, plane checker, pointer, finger, or some combination thereof.

Resection Equipment 110 (not shown in FIG. 1) performs bone or tissueresection using, for example, mechanical, ultrasonic, or lasertechniques. Examples of Resection Equipment 110 include drillingdevices, burring devices, oscillatory sawing devices, vibratoryimpaction devices, reamers, ultrasonic bone cutting devices, radiofrequency ablation devices, reciprocating devices (such as a rasp orbroach), and laser ablation systems. In some embodiments, the ResectionEquipment 110 is held and operated by the surgeon during surgery. Inother embodiments, the Effector Platform 105 may be used to hold theResection Equipment 110 during use.

The Effector Platform 105 can also include a cutting guide or jig 105Dthat is used to guide saws or drills used to resect tissue duringsurgery. Such cutting guides 105D can be formed integrally as part ofthe Effector Platform 105 or Robotic Arm 105A, or cutting guides can beseparate structures that can be matingly and/or removably attached tothe Effector Platform 105 or Robotic Arm 105A. The Effector Platform 105or Robotic Arm 105A can be controlled by the CASS 100 to position acutting guide or jig 105D adjacent to the patient's anatomy inaccordance with a pre-operatively or intraoperatively developed surgicalplan such that the cutting guide or jig will produce a precise bone cutin accordance with the surgical plan.

The Tracking System 115 uses one or more sensors to collect real-timeposition data that locates the patient's anatomy and surgicalinstruments. For example, for TKA procedures, the Tracking System mayprovide a location and orientation of the End Effector 105B during theprocedure. In addition to positional data, data from the Tracking System115 can also be used to infer velocity/acceleration ofanatomy/instrumentation, which can be used for tool control. In someembodiments, the Tracking System 115 may use a tracker array attached tothe End Effector 105B to determine the location and orientation of theEnd Effector 105B. The position of the End Effector 105B may be inferredbased on the position and orientation of the Tracking System 115 and aknown relationship in three-dimensional space between the TrackingSystem 115 and the End Effector 105B. Various types of tracking systemsmay be used in various embodiments of the present invention including,without limitation, Infrared (IR) tracking systems, electromagnetic (EM)tracking systems, video or image based tracking systems, and ultrasoundregistration and tracking systems. Using the data provided by thetracking system 115, the surgical computer 150 can detect objects andprevent collision. For example, the surgical computer 150 can preventthe Robotic Arm 105A from colliding with soft tissue.

Any suitable tracking system can be used for tracking surgical objectsand patient anatomy in the surgical theatre. For example, a combinationof IR and visible light cameras can be used in an array. Variousillumination sources, such as an IR LED light source, can illuminate thescene allowing three-dimensional imaging to occur. In some embodiments,this can include stereoscopic, tri-scopic, quad-scopic, etc. imaging. Inaddition to the camera array, which in some embodiments is affixed to acart, additional cameras can be placed throughout the surgical theatre.For example, handheld tools or headsets worn by operators/surgeons caninclude imaging capability that communicates images back to a centralprocessor to correlate those images with images captured by the cameraarray. This can give a more robust image of the environment for modelingusing multiple perspectives. Furthermore, some imaging devices may be ofsuitable resolution or have a suitable perspective on the scene to pickup information stored in quick response (QR) codes or barcodes. This canbe helpful in identifying specific objects not manually registered withthe system. In some embodiments, the camera may be mounted on theRobotic Arm 105A.

Although, as discussed herein, the majority of tracking and/ornavigation techniques utilize image-based tracking systems (e.g., IRtracking systems, video or image based tracking systems, etc.). However,electromagnetic (EM) based tracking systems are becoming more common fora variety of reasons. For example, implantation of standard opticaltrackers requires tissue resection (e.g., down to the cortex) as well assubsequent drilling and driving of cortical pins. Additionally, becauseoptical trackers require a direct line of site with a tracking system,the placement of such trackers may need to be far from the surgical siteto ensure they do not restrict the movement of a surgeon or medicalprofessional.

Generally, EM based tracking devices include one or more wire coils anda reference field generator. The one or more wire coils may be energized(e.g., via a wired or wireless power supply). Once energized, the coilcreates an electromagnetic field that can be detected and measured(e.g., by the reference field generator or an additional device) in amanner that allows for the location and orientation of the one or morewire coils to be determined. As should be understood by someone ofordinary skill in the art, a single coil, such as is shown in FIG. 2, islimited to detecting five (5) total degrees-of-freedom (DOF). Forexample, sensor 200 may be able to track/determine movement in the X, Y,or Z direction, as well as rotation around the Y-axis 202 or Z-axis 201.However, because of the electromagnetic properties of a coil, it is notpossible to properly track rotational movement around the X axis.

Accordingly, in most electromagnetic tracking applications, a three coilsystem, such as that shown in FIG. 3A is used to enable tracking in allsix degrees of freedom that are possible for a rigid body moving in athree-dimensional space (i.e., forward/backward 310, up/down 320,left/right 330, roll 340, pitch 350, and yaw 360). However, theinclusion of two additional coils and the 90° offset angles at whichthey are positioned may require the tracking device to be much larger.Alternatively, as one of skill in the art would know, less than threefull coils may be used to track all 6DOF. In some EM based trackingdevices, two coils may be affixed to each other, such as is shown inFIG. 3B. Because the two coils 301B and 302B are rigidly affixed to eachother, not perfectly parallel, and have locations that are knownrelative to each other, it is possible to determine the sixth degree offreedom 303B with this arrangement.

Although the use of two affixed coils (e.g., 301B and 302B) allows forEM based tracking in 6DOF, the sensor device is substantially larger indiameter than a single coil because of the additional coil. Thus, thepractical application of using an EM based tracking system in a surgicalenvironment may require tissue resection and drilling of a portion ofthe patient bone to allow for insertion of a EM tracker. Alternatively,in some embodiments, it may be possible to implant/insert a single coil,or 5DOF EM tracking device, into a patient bone using only a pin (e.g.,without the need to drill or carve out substantial bone).

Thus, as described herein, a solution is needed for which the use of anEM tracking system can be restricted to devices small enough to beinserted/embedded using a small diameter needle or pin (i.e., withoutthe need to create a new incision or large diameter opening in thebone). Accordingly, in some embodiments, a second 5DOF sensor, which isnot attached to the first, and thus has a small diameter, may be used totrack all 6DOF. Referring now to FIG. 3C, in some embodiments, two 5DOFEM sensors (e.g., 301C and 302C) may be inserted into the patient (e.g.,in a patient bone) at different locations and with different angularorientations (e.g., angle 303C is non-zero).

Referring now to FIG. 4, an example embodiment is shown in which a first5DOF EM sensor 401 and a second 5DOF EM sensor 402 are inserted into thepatient bone 403 using a standard hollow needle 405 that is typical inmost OR(s). In a further embodiment, the first sensor 401 and the secondsensor 402 may have an angle offset of “?” 404. In some embodiments, itmay be necessary for the offset angle “?” 404 to be greater than apredetermined value (e.g., a minimum angle of 0.50°, 0.75°, etc.). Thisminimum value may, in some embodiments, be determined by the CASS andprovided to the surgeon or medical professional during the surgicalplan. In some embodiments, a minimum value may be based on one or morefactors, such as, for example, the orientation accuracy of the trackingsystem, a distance between the first and second EM sensors. The locationof the field generator, a location of the field detector, a type of EMsensor, a quality of the EM sensor, patient anatomy, and the like.

Accordingly, as discussed herein, in some embodiments, a pin/needle(e.g., a cannulated mounting needle, etc.) may be used to insert one ormore EM sensors. Generally, the pin/needle would be a disposablecomponent, while the sensors themselves may be reusable. However, itshould be understood that this is only one potential system, and thatvarious other systems may be used in which the pin/needle and/or EMsensors are independently disposable or reusable. In a furtherembodiment, the EM sensors may be affixed to the mounting needle/pin(e.g., using a luer-lock fitting or the like), which can allow for quickassembly and disassembly. In additional embodiments, the EM sensors mayutilize an alternative sleeve and/or anchor system that allows forminimally invasive placement of the sensors.

In another embodiment, the above systems may allow for a multi-sensornavigation system that can detect and correct for field distortions thatplague electromagnetic tracking systems. It should be understood thatfield distortions may result from movement of any ferromagneticmaterials within the reference field. Thus, as one of ordinary skill inthe art would know, a typical OR has a large number of devices (e.g., anoperating table, LCD displays, lighting equipment, imaging systems,surgical instruments, etc.) that may cause interference. Furthermore,field distortions are notoriously difficult to detect. The use ofmultiple EM sensors enables the system to detect field distortionsaccurately, and/or to warn a user that the current position measurementsmay not be accurate. Because the sensors are rigidly fixed to the bonyanatomy (e.g., via the pin/needle), relative measurement of sensorpositions (X, Y, Z) may be used to detect field distortions. By way ofnon-limiting example, in some embodiments, after the EM sensors arefixed to the bone, the relative distance between the two sensors isknown and should remain constant. Thus, any change in this distancecould indicate the presence of a field distortion.

In some embodiments, specific objects can be manually registered by asurgeon with the system preoperatively or intraoperatively. For example,by interacting with a user interface, a surgeon may identify thestarting location for a tool or a bone structure. By tracking fiducialmarks associated with that tool or bone structure, or by using otherconventional image tracking modalities, a processor may track that toolor bone as it moves through the environment in a three-dimensionalmodel.

In some embodiments, certain markers, such as fiducial marks thatidentify individuals, important tools, or bones in the theater mayinclude passive or active identifiers that can be picked up by a cameraor camera array associated with the tracking system. For example, an IRLED can flash a pattern that conveys a unique identifier to the sourceof that pattern, providing a dynamic identification mark. Similarly, oneor two dimensional optical codes (barcode, QR code, etc.) can be affixedto objects in the theater to provide passive identification that canoccur based on image analysis. If these codes are placed asymmetricallyon an object, they can also be used to determine an orientation of anobject by comparing the location of the identifier with the extents ofan object in an image. For example, a QR code may be placed in a cornerof a tool tray, allowing the orientation and identity of that tray to betracked. Other tracking modalities are explained throughout. Forexample, in some embodiments, augmented reality headsets can be worn bysurgeons and other staff to provide additional camera angles andtracking capabilities.

In addition to optical tracking, certain features of objects can betracked by registering physical properties of the object and associatingthem with objects that can be tracked, such as fiducial marks fixed to atool or bone. For example, a surgeon may perform a manual registrationprocess whereby a tracked tool and a tracked bone can be manipulatedrelative to one another. By impinging the tip of the tool against thesurface of the bone, a three-dimensional surface can be mapped for thatbone that is associated with a position and orientation relative to theframe of reference of that fiducial mark. By optically tracking theposition and orientation (pose) of the fiducial mark associated withthat bone, a model of that surface can be tracked with an environmentthrough extrapolation.

The registration process that registers the CASS 100 to the relevantanatomy of the patient can also involve the use of anatomical landmarks,such as landmarks on a bone or cartilage. For example, the CASS 100 caninclude a 3D model of the relevant bone or joint and the surgeon canintraoperatively collect data regarding the location of bony landmarkson the patient's actual bone using a probe that is connected to theCASS. Bony landmarks can include, for example, the medial malleolus andlateral malleolus, the ends of the proximal femur and distal tibia, andthe center of the hip joint. The CASS 100 can compare and register thelocation data of bony landmarks collected by the surgeon with the probewith the location data of the same landmarks in the 3D model.Alternatively, the CASS 100 can construct a 3D model of the bone orjoint without pre-operative image data by using location data of bonylandmarks and the bone surface that are collected by the surgeon using aCASS probe or other means. The registration process can also includedetermining various axes of a joint. For example, for a TKA the surgeoncan use the CASS 100 to determine the anatomical and mechanical axes ofthe femur and tibia. The surgeon and the CASS 100 can identify thecenter of the hip joint by moving the patient's leg in a spiraldirection (i.e., circumduction) so the CASS can determine where thecenter of the hip joint is located.

A Tissue Navigation System 120 (not shown in FIG. 1) provides thesurgeon with intraoperative, real-time visualization for the patient'sbone, cartilage, muscle, nervous, and/or vascular tissues surroundingthe surgical area. Examples of systems that may be employed for tissuenavigation include fluorescent imaging systems and ultrasound systems.

The Display 125 provides graphical user interfaces (GUIs) that displayimages collected by the Tissue Navigation System 120 as well otherinformation relevant to the surgery. For example, in one embodiment, theDisplay 125 overlays image information collected from various modalities(e.g., CT, MRI, X-ray, fluorescent, ultrasound, etc.) collectedpre-operatively or intra-operatively to give the surgeon various viewsof the patient's anatomy as well as real-time conditions. The Display125 may include, for example, one or more computer monitors. As analternative or supplement to the Display 125, one or more members of thesurgical staff may wear an Augmented Reality (AR) Head Mounted Device(HMD). For example, in FIG. 1 the Surgeon 111 is wearing an AR HMD 155that may, for example, overlay pre-operative image data on the patientor provide surgical planning suggestions. Various example uses of the ARHMD 155 in surgical procedures are detailed in the sections that follow.

Surgical Computer 150 provides control instructions to variouscomponents of the CASS 100, collects data from those components, andprovides general processing for various data needed during surgery. Insome embodiments, the Surgical Computer 150 is a general purposecomputer. In other embodiments, the Surgical Computer 150 may be aparallel computing platform that uses multiple central processing units(CPUs) or graphics processing units (GPU) to perform processing. In someembodiments, the Surgical Computer 150 is connected to a remote serverover one or more computer networks (e.g., the Internet). The remoteserver can be used, for example, for storage of data or execution ofcomputationally intensive processing tasks.

Various techniques generally known in the art can be used for connectingthe Surgical Computer 150 to the other components of the CASS 100.Moreover, the computers can connect to the Surgical Computer 150 using amix of technologies. For example, the End Effector 105B may connect tothe Surgical Computer 150 over a wired (i.e., serial) connection. TheTracking System 115, Tissue Navigation System 120, and Display 125 cansimilarly be connected to the Surgical Computer 150 using wiredconnections. Alternatively, the Tracking System 115, Tissue NavigationSystem 120, and Display 125 may connect to the Surgical Computer 150using wireless technologies such as, without limitation, Wi-Fi,Bluetooth, Near Field Communication (NFC), or ZigBee.

Powered Impaction and Acetabular Reamer Devices

Part of the flexibility of the CASS design described above with respectto FIG. 1 is that additional or alternative devices can be added to theCASS 100 as necessary to support particular surgical procedures. Forexample, in the context of hip surgeries, the CASS 100 may include apowered impaction device. Impaction devices are designed to repeatedlyapply an impaction force that the surgeon can use to perform activitiessuch as implant alignment. For example, within a total hip arthroplasty(THA), a surgeon will often insert a prosthetic acetabular cup into theimplant host's acetabulum using an impaction device. Although impactiondevices can be manual in nature (e.g., operated by the surgeon strikingan impactor with a mallet), powered impaction devices are generallyeasier and quicker to use in the surgical setting. Powered impactiondevices may be powered, for example, using a battery attached to thedevice. Various attachment pieces may be connected to the poweredimpaction device to allow the impaction force to be directed in variousways as needed during surgery. Also in the context of hip surgeries, theCASS 100 may include a powered, robotically controlled end effector toream the acetabulum to accommodate an acetabular cup implant.

In a robotically-assisted THA, the patient's anatomy can be registeredto the CASS 100 using CT or other image data, the identification ofanatomical landmarks, tracker arrays attached to the patient's bones,and one or more cameras. Tracker arrays can be mounted on the iliaccrest using clamps and/or bone pins and such trackers can be mountedexternally through the skin or internally (either posterolaterally oranterolaterally) through the incision made to perform the THA. For aTHA, the CASS 100 can utilize one or more femoral cortical screwsinserted into the proximal femur as checkpoints to aid in theregistration process. The CASS 100 can also utilize one or morecheckpoint screws inserted into the pelvis as additional checkpoints toaid in the registration process. Femoral tracker arrays can be securedto or mounted in the femoral cortical screws. The CASS 100 can employsteps where the registration is verified using a probe that the surgeonprecisely places on key areas of the proximal femur and pelvisidentified for the surgeon on the display 125. Trackers can be locatedon the robotic arm 105A or end effector 105B to register the arm and/orend effector to the CASS 100. The verification step can also utilizeproximal and distal femoral checkpoints. The CASS 100 can utilize colorprompts or other prompts to inform the surgeon that the registrationprocess for the relevant bones and the robotic arm 105A or end effector105B has been verified to a certain degree of accuracy (e.g., within 1mm).

For a THA, the CASS 100 can include a broach tracking option usingfemoral arrays to allow the surgeon to intraoperatively capture thebroach position and orientation and calculate hip length and offsetvalues for the patient. Based on information provided about thepatient's hip joint and the planned implant position and orientationafter broach tracking is completed, the surgeon can make modificationsor adjustments to the surgical plan.

For a robotically-assisted THA, the CASS 100 can include one or morepowered reamers connected or attached to a robotic arm 105A or endeffector 105B that prepares the pelvic bone to receive an acetabularimplant according to a surgical plan. The robotic arm 105A and/or endeffector 105B can inform the surgeon and/or control the power of thereamer to ensure that the acetabulum is being resected (reamed) inaccordance with the surgical plan. For example, if the surgeon attemptsto resect bone outside of the boundary of the bone to be resected inaccordance with the surgical plan, the CASS 100 can power off the reameror instruct the surgeon to power off the reamer. The CASS 100 canprovide the surgeon with an option to turn off or disengage the roboticcontrol of the reamer. The display 125 can depict the progress of thebone being resected (reamed) as compared to the surgical plan usingdifferent colors. The surgeon can view the display of the bone beingresected (reamed) to guide the reamer to complete the reaming inaccordance with the surgical plan. The CASS 100 can provide visual oraudible prompts to the surgeon to warn the surgeon that resections arebeing made that are not in accordance with the surgical plan.

Following reaming, the CASS 100 can employ a manual or powered impactorthat is attached or connected to the robotic arm 105A or end effector105B to impact trial implants and final implants into the acetabulum.The robotic arm 105A and/or end effector 105B can be used to guide theimpactor to impact the trial and final implants into the acetabulum inaccordance with the surgical plan. The CASS 100 can cause the positionand orientation of the trial and final implants vis-à-vis the bone to bedisplayed to inform the surgeon as to how the trial and final implant'sorientation and position compare to the surgical plan, and the display125 can show the implant's position and orientation as the surgeonmanipulates the leg and hip. The CASS 100 can provide the surgeon withthe option of re-planning and re-doing the reaming and implant impactionby preparing a new surgical plan if the surgeon is not satisfied withthe original implant position and orientation.

Preoperatively, the CASS 100 can develop a proposed surgical plan basedon a three dimensional model of the hip joint and other informationspecific to the patient, such as the mechanical and anatomical axes ofthe leg bones, the epicondylar axis, the femoral neck axis, thedimensions (e.g., length) of the femur and hip, the midline axis of thehip joint, the ASIS axis of the hip joint, and the location ofanatomical landmarks such as the lesser trochanter landmarks, the distallandmark, and the center of rotation of the hip joint. TheCASS-developed surgical plan can provide a recommended optimal implantsize and implant position and orientation based on the three dimensionalmodel of the hip joint and other information specific to the patient.The CASS-developed surgical plan can include proposed details on offsetvalues, inclination and anteversion values, center of rotation, cupsize, medialization values, superior-inferior fit values, femoral stemsizing and length.

For a THA, the CASS-developed surgical plan can be viewed preoperativelyand intraoperatively, and the surgeon can modify CASS-developed surgicalplan preoperatively or intraoperatively. The CASS-developed surgicalplan can display the planned resection to the hip joint and superimposethe planned implants onto the hip joint based on the planned resections.The CASS 100 can provide the surgeon with options for different surgicalworkflows that will be displayed to the surgeon based on a surgeon'spreference. For example, the surgeon can choose from different workflowsbased on the number and types of anatomical landmarks that are checkedand captured and/or the location and number of tracker arrays used inthe registration process.

According to some embodiments, a powered impaction device used with theCASS 100 may operate with a variety of different settings. In someembodiments, the surgeon adjusts settings through a manual switch orother physical mechanism on the powered impaction device. In otherembodiments, a digital interface may be used that allows setting entry,for example, via a touchscreen on the powered impaction device. Such adigital interface may allow the available settings to vary based, forexample, on the type of attachment piece connected to the powerattachment device. In some embodiments, rather than adjusting thesettings on the powered impaction device itself, the settings can bechanged through communication with a robot or other computer systemwithin the CASS 100. Such connections may be established using, forexample, a Bluetooth or Wi-Fi networking module on the powered impactiondevice. In another embodiment, the impaction device and end pieces maycontain features that allow the impaction device to be aware of what endpiece (cup impactor, broach handle, etc.) is attached with no actionrequired by the surgeon, and adjust the settings accordingly. This maybe achieved, for example, through a QR code, barcode, RFID tag, or othermethod.

Examples of the settings that may be used include cup impaction settings(e.g., single direction, specified frequency range, specified forceand/or energy range); broach impaction settings (e.g., dualdirection/oscillating at a specified frequency range, specified forceand/or energy range); femoral head impaction settings (e.g., singledirection/single blow at a specified force or energy); and stemimpaction settings (e.g., single direction at specified frequency with aspecified force or energy). Additionally, in some embodiments, thepowered impaction device includes settings related to acetabular linerimpaction (e.g., single direction/single blow at a specified force orenergy). There may be a plurality of settings for each type of linersuch as poly, ceramic, oxinium, or other materials. Furthermore, thepowered impaction device may offer settings for different bone qualitybased on preoperative testing/imaging/knowledge and/or intraoperativeassessment by surgeon. In some embodiments, the powered impactor devicemay have a dual function. For example, the powered impactor device notonly could provide reciprocating motion to provide an impact force, butalso could provide reciprocating motion for a broach or rasp.

In some embodiments, the powered impaction device includes feedbacksensors that gather data during instrument use, and send data to acomputing device such as a controller within the device or the SurgicalComputer 150. This computing device can then record the data for lateranalysis and use. Examples of the data that may be collected include,without limitation, sound waves, the predetermined resonance frequencyof each instrument, reaction force or rebound energy from patient bone,location of the device with respect to imaging (e.g., fluoro, CT,ultrasound, MRI, etc.) registered bony anatomy, and/or external straingauges on bones.

Once the data is collected, the computing device may execute one or morealgorithms in real-time or near real-time to aid the surgeon inperforming the surgical procedure. For example, in some embodiments, thecomputing device uses the collected data to derive information such asthe proper final broach size (femur); when the stem is fully seated(femur side); or when the cup is seated (depth and/or orientation) for aTHA. Once the information is known, it may be displayed for thesurgeon's review, or it may be used to activate haptics or otherfeedback mechanisms to guide the surgical procedure.

Additionally, the data derived from the aforementioned algorithms may beused to drive operation of the device. For example, during insertion ofa prosthetic acetabular cup with a powered impaction device, the devicemay automatically extend an impaction head (e.g., an end effector)moving the implant into the proper location, or turn the power off tothe device once the implant is fully seated. In one embodiment, thederived information may be used to automatically adjust settings forquality of bone where the powered impaction device should use less powerto mitigate femoral/acetabular/pelvic fracture or damage to surroundingtissues.

Robotic Arm

In some embodiments, the CASS 100 includes a robotic arm 105A thatserves as an interface to stabilize and hold a variety of instrumentsused during the surgical procedure. For example, in the context of a hipsurgery, these instruments may include, without limitation, retractors,a sagittal or reciprocating saw, the reamer handle, the cup impactor,the broach handle, and the stem inserter. The robotic arm 105A may havemultiple degrees of freedom (like a Spider device), and have the abilityto be locked in place (e.g., by a press of a button, voice activation, asurgeon removing a hand from the robotic arm, or other method).

In some embodiments, movement of the robotic arm 105A may be effectuatedby use of a control panel built into the robotic arm system. Forexample, a display screen may include one or more input sources, such asphysical buttons or a user interface having one or more icons, thatdirect movement of the robotic arm 105A. The surgeon or other healthcareprofessional may engage with the one or more input sources to positionthe robotic arm 105A when performing a surgical procedure.

A tool or an end effector 105B attached or integrated into a robotic arm105A may include, without limitation, a burring device, a scalpel, acutting device, a retractor, a joint tensioning device, or the like. Inembodiments in which an end effector 105B is used, the end effector maybe positioned at the end of the robotic arm 105A such that any motorcontrol operations are performed within the robotic arm system. Inembodiments in which a tool is used, the tool may be secured at a distalend of the robotic arm 105A, but motor control operation may residewithin the tool itself.

The robotic arm 105A may be motorized internally to both stabilize therobotic arm, thereby preventing it from falling and hitting the patient,surgical table, surgical staff, etc., and to allow the surgeon to movethe robotic arm without having to fully support its weight. While thesurgeon is moving the robotic arm 105A, the robotic arm may provide someresistance to prevent the robotic arm from moving too fast or having toomany degrees of freedom active at once. The position and the lock statusof the robotic arm 105A may be tracked, for example, by a controller orthe Surgical Computer 150.

In some embodiments, the robotic arm 105A can be moved by hand (e.g., bythe surgeon) or with internal motors into its ideal position andorientation for the task being performed. In some embodiments, therobotic arm 105A may be enabled to operate in a “free” mode that allowsthe surgeon to position the arm into a desired position without beingrestricted. While in the free mode, the position and orientation of therobotic arm 105A may still be tracked as described above. In oneembodiment, certain degrees of freedom can be selectively released uponinput from user (e.g., surgeon) during specified portions of thesurgical plan tracked by the Surgical Computer 150. Designs in which arobotic arm 105A is internally powered through hydraulics or motors orprovides resistance to external manual motion through similar means canbe described as powered robotic arms, while arms that are manuallymanipulated without power feedback, but which may be manually orautomatically locked in place, may be described as passive robotic arms.

A robotic arm 105A or end effector 105B can include a trigger or othermeans to control the power of a saw or drill. Engagement of the triggeror other means by the surgeon can cause the robotic arm 105A or endeffector 105B to transition from a motorized alignment mode to a modewhere the saw or drill is engaged and powered on. Additionally, the CASS100 can include a foot pedal (not shown) that causes the system toperform certain functions when activated. For example, the surgeon canactivate the foot pedal to instruct the CASS 100 to place the roboticarm 105A or end effector 105B in an automatic mode that brings therobotic arm or end effector into the proper position with respect to thepatient's anatomy in order to perform the necessary resections. The CASS100 can also place the robotic arm 105A or end effector 105B in acollaborative mode that allows the surgeon to manually manipulate andposition the robotic arm or end effector into a particular location. Thecollaborative mode can be configured to allow the surgeon to move therobotic arm 105A or end effector 105B medially or laterally, whilerestricting movement in other directions. As discussed, the robotic arm105A or end effector 105B can include a cutting device (saw, drill, andburr) or a cutting guide or jig 105D that will guide a cutting device.In other embodiments, movement of the robotic arm 105A or roboticallycontrolled end effector 105B can be controlled entirely by the CASS 100without any, or with only minimal, assistance or input from a surgeon orother medical professional. In still other embodiments, the movement ofthe robotic arm 105A or robotically controlled end effector 105B can becontrolled remotely by a surgeon or other medical professional using acontrol mechanism separate from the robotic arm or roboticallycontrolled end effector device, for example using a joystick orinteractive monitor or display control device.

The examples below describe uses of the robotic device in the context ofa hip surgery; however, it should be understood that the robotic arm mayhave other applications for surgical procedures involving knees,shoulders, etc. One example of use of a robotic arm in the context offorming an anterior cruciate ligament (ACL) graft tunnel is described inU.S. Provisional Patent Application No. 62/723,898 filed Aug. 28, 2018and entitled “Robotic Assisted Ligament Graft Placement and Tensioning,”the entirety of which is incorporated herein by reference.

A robotic arm 105A may be used for holding the retractor. For example inone embodiment, the robotic arm 105A may be moved into the desiredposition by the surgeon. At that point, the robotic arm 105A may lockinto place. In some embodiments, the robotic arm 105A is provided withdata regarding the patient's position, such that if the patient moves,the robotic arm can adjust the retractor position accordingly. In someembodiments, multiple robotic arms may be used, thereby allowingmultiple retractors to be held or for more than one activity to beperformed simultaneously (e.g., retractor holding & reaming).

The robotic arm 105A may also be used to help stabilize the surgeon'shand while making a femoral neck cut. In this application, control ofthe robotic arm 105A may impose certain restrictions to prevent softtissue damage from occurring. For example, in one embodiment, theSurgical Computer 150 tracks the position of the robotic arm 105A as itoperates. If the tracked location approaches an area where tissue damageis predicted, a command may be sent to the robotic arm 105A causing itto stop. Alternatively, where the robotic arm 105A is automaticallycontrolled by the Surgical Computer 150, the Surgical Computer mayensure that the robotic arm is not provided with any instructions thatcause it to enter areas where soft tissue damage is likely to occur. TheSurgical Computer 150 may impose certain restrictions on the surgeon toprevent the surgeon from reaming too far into the medial wall of theacetabulum or reaming at an incorrect angle or orientation.

In some embodiments, the robotic arm 105A may be used to hold a cupimpactor at a desired angle or orientation during cup impaction. Whenthe final position has been achieved, the robotic arm 105A may preventany further seating to prevent damage to the pelvis.

The surgeon may use the robotic arm 105A to position the broach handleat the desired position and allow the surgeon to impact the broach intothe femoral canal at the desired orientation. In some embodiments, oncethe Surgical Computer 150 receives feedback that the broach is fullyseated, the robotic arm 105A may restrict the handle to prevent furtheradvancement of the broach.

The robotic arm 105A may also be used for resurfacing applications. Forexample, the robotic arm 105A may stabilize the surgeon while usingtraditional instrumentation and provide certain restrictions orlimitations to allow for proper placement of implant components (e.g.,guide wire placement, chamfer cutter, sleeve cutter, plan cutter, etc.).Where only a burr is employed, the robotic arm 105A may stabilize thesurgeon's handpiece and may impose restrictions on the handpiece toprevent the surgeon from removing unintended bone in contravention ofthe surgical plan.

The robotic arm 105A may be a passive arm. As an example, the roboticarm 105A may be a CIRQ robot arm available from Brainlab AG. CIRQ is aregistered trademark of Brainlab AG, Olof-Palme-Str. 9 81829, Munchen,FED REP of GERMANY. In one particular embodiment, the robotic arm 105Ais an intelligent holding arm as disclosed in U.S. patent applicationSer. No. 15/525,585 to Krinninger et al., U.S. patent application Ser.No. 15/561,042 to Nowatschin et al., U.S. patent application Ser. No.15/561,048 to Nowatschin et al., and U.S. Pat. No. 10,342,636 toNowatschin et al., the entire contents of each of which is hereinincorporated by reference.

Surgical Procedure Data Generation and Collection

The various services that are provided by medical professionals to treata clinical condition are collectively referred to as an “episode ofcare.” For a particular surgical intervention the episode of care caninclude three phases: pre-operative, intra-operative, andpost-operative. During each phase, data is collected or generated thatcan be used to analyze the episode of care in order to understandvarious aspects of the procedure and identify patterns that may be used,for example, in training models to make decisions with minimal humanintervention. The data collected over the episode of care may be storedat the Surgical Computer 150 or the Surgical Data Server 180 as acomplete dataset. Thus, for each episode of care, a dataset exists thatcomprises all of the data collectively pre-operatively about thepatient, all of the data collected or stored by the CASS 100intra-operatively, and any post-operative data provided by the patientor by a healthcare professional monitoring the patient.

As explained in further detail, the data collected during the episode ofcare may be used to enhance performance of the surgical procedure or toprovide a holistic understanding of the surgical procedure and thepatient outcomes. For example, in some embodiments, the data collectedover the episode of care may be used to generate a surgical plan. In oneembodiment, a high-level, pre-operative plan is refinedintra-operatively as data is collected during surgery. In this way, thesurgical plan can be viewed as dynamically changing in real-time or nearreal-time as new data is collected by the components of the CASS 100. Inother embodiments, pre-operative images or other input data may be usedto develop a robust plan preoperatively that is simply executed duringsurgery. In this case, the data collected by the CASS 100 during surgerymay be used to make recommendations that ensure that the surgeon stayswithin the pre-operative surgical plan. For example, if the surgeon isunsure how to achieve a certain prescribed cut or implant alignment, theSurgical Computer 150 can be queried for a recommendation. In stillother embodiments, the pre-operative and intra-operative planningapproaches can be combined such that a robust pre-operative plan can bedynamically modified, as necessary or desired, during the surgicalprocedure. In some embodiments, a biomechanics-based model of patientanatomy contributes simulation data to be considered by the CASS 100 indeveloping preoperative, intraoperative, andpost-operative/rehabilitation procedures to optimize implant performanceoutcomes for the patient.

Aside from changing the surgical procedure itself, the data gatheredduring the episode of care may be used as an input to other proceduresancillary to the surgery. For example, in some embodiments, implants canbe designed using episode of care data. Example data-driven techniquesfor designing, sizing, and fitting implants are described in U.S. patentapplication Ser. No. 13/814,531 filed Aug. 15, 2011 and entitled“Systems and Methods for Optimizing Parameters for OrthopaedicProcedures”; U.S. patent application Ser. No. 14/232,958 filed Jul. 20,2012 and entitled “Systems and Methods for Optimizing Fit of an Implantto Anatomy”; and U.S. patent application Ser. No. 12/234,444 filed Sep.19, 2008 and entitled “Operatively Tuning Implants for IncreasedPerformance,” the entire contents of each of which are herebyincorporated by reference into this patent application.

Furthermore, the data can be used for educational, training, or researchpurposes. For example, using the network-based approach described belowin FIG. 5C, other doctors or students can remotely view surgeries ininterfaces that allow them to selectively view data as it is collectedfrom the various components of the CASS 100. After the surgicalprocedure, similar interfaces may be used to “playback” a surgery fortraining or other educational purposes, or to identify the source of anyissues or complications with the procedure.

Data acquired during the pre-operative phase generally includes allinformation collected or generated prior to the surgery. Thus, forexample, information about the patient may be acquired from a patientintake form or electronic medical record (EMR). Examples of patientinformation that may be collected include, without limitation, patientdemographics, diagnoses, medical histories, progress notes, vital signs,medical history information, allergies, and lab results. Thepre-operative data may also include images related to the anatomicalarea of interest. These images may be captured, for example, usingMagnetic Resonance Imaging (MRI), Computed Tomography (CT), X-ray,ultrasound, or any other modality known in the art. The pre-operativedata may also comprise quality of life data captured from the patient.For example, in one embodiment, pre-surgery patients use a mobileapplication (“app”) to answer questionnaires regarding their currentquality of life. In some embodiments, preoperative data used by the CASS100 includes demographic, anthropometric, cultural, or other specifictraits about a patient that can coincide with activity levels andspecific patient activities to customize the surgical plan to thepatient. For example, certain cultures or demographics may be morelikely to use a toilet that requires squatting on a daily basis.

FIGS. 5A and 5B provide examples of data that may be acquired during theintra-operative phase of an episode of care. These examples are based onthe various components of the CASS 100 described above with reference toFIG. 1; however, it should be understood that other types of data may beused based on the types of equipment used during surgery and their use.

FIG. 5A shows examples of some of the control instructions that theSurgical Computer 150 provides to other components of the CASS 100,according to some embodiments. Note that the example of FIG. 5A assumesthat the components of the Effector Platform 105 are each controlleddirectly by the Surgical Computer 150. In embodiments where a componentis manually controlled by the Surgeon 111, instructions may be providedon the Display 125 or AR HMD 155 instructing the Surgeon 111 how to movethe component.

The various components included in the Effector Platform 105 arecontrolled by the Surgical Computer 150 providing position commands thatinstruct the component where to move within a coordinate system. In someembodiments, the Surgical Computer 150 provides the Effector Platform105 with instructions defining how to react when a component of theEffector Platform 105 deviates from a surgical plan. These commands arereferenced in FIG. 5A as “haptic” commands. For example, the EndEffector 105B may provide a force to resist movement outside of an areawhere resection is planned. Other commands that may be used by theEffector Platform 105 include vibration and audio cues.

In some embodiments, the end effectors 105B of the robotic arm 105A areoperatively coupled with cutting guide 105D. In response to ananatomical model of the surgical scene, the robotic arm 105A can movethe end effectors 105B and the cutting guide 105D into position to matchthe location of the femoral or tibial cut to be performed in accordancewith the surgical plan. This can reduce the likelihood of error,allowing the vision system and a processor utilizing that vision systemto implement the surgical plan to place a cutting guide 105D at theprecise location and orientation relative to the tibia or femur to aligna cutting slot of the cutting guide with the cut to be performedaccording to the surgical plan. Then, a surgeon can use any suitabletool, such as an oscillating or rotating saw or drill to perform the cut(or drill a hole) with perfect placement and orientation because thetool is mechanically limited by the features of the cutting guide 105D.In some embodiments, the cutting guide 105D may include one or more pinholes that are used by a surgeon to drill and screw or pin the cuttingguide into place before performing a resection of the patient tissueusing the cutting guide. This can free the robotic arm 105A or ensurethat the cutting guide 105D is fully affixed without moving relative tothe bone to be resected. For example, this procedure can be used to makethe first distal cut of the femur during a total knee arthroplasty. Insome embodiments, where the arthroplasty is a hip arthroplasty, cuttingguide 105D can be fixed to the femoral head or the acetabulum for therespective hip arthroplasty resection. It should be understood that anyarthroplasty that utilizes precise cuts can use the robotic arm 105Aand/or cutting guide 105D in this manner.

The Resection Equipment 110 is provided with a variety of commands toperform bone or tissue operations. As with the Effector Platform 105,position information may be provided to the Resection Equipment 110 tospecify where it should be located when performing resection. Othercommands provided to the Resection Equipment 110 may be dependent on thetype of resection equipment. For example, for a mechanical or ultrasonicresection tool, the commands may specify the speed and frequency of thetool. For Radiofrequency Ablation (RFA) and other laser ablation tools,the commands may specify intensity and pulse duration.

Some components of the CASS 100 do not need to be directly controlled bythe Surgical Computer 150; rather, the Surgical Computer 150 only needsto activate the component, which then executes software locallyspecifying the manner in which to collect data and provide it to theSurgical Computer 150. In the example of FIG. 5A, there are twocomponents that are operated in this manner: the Tracking System 115 andthe Tissue Navigation System 120.

The Surgical Computer 150 provides the Display 125 with anyvisualization that is needed by the Surgeon 111 during surgery. Formonitors, the Surgical Computer 150 may provide instructions fordisplaying images, GUIs, etc. using techniques known in the art. Thedisplay 125 can include various aspects of the workflow of a surgicalplan. During the registration process, for example, the display 125 canshow a preoperatively constructed 3D bone model and depict the locationsof the probe as the surgeon uses the probe to collect locations ofanatomical landmarks on the patient. The display 125 can includeinformation about the surgical target area. For example, in connectionwith a TKA, the display 125 can depict the mechanical and anatomicalaxes of the femur and tibia. The display 125 can depict varus and valgusangles for the knee joint based on a surgical plan, and the CASS 100 candepict how such angles will be affected if contemplated revisions to thesurgical plan are made. Accordingly, the display 125 is an interactiveinterface that can dynamically update and display how changes to thesurgical plan would impact the procedure and the final position andorientation of implants installed on bone.

As the workflow progresses to preparation of bone cuts or resections,the display 125 can depict the planned or recommended bone cuts beforeany cuts are performed. The surgeon 111 can manipulate the image displayto provide different anatomical perspectives of the target area and canhave the option to alter or revise the planned bone cuts based onintraoperative evaluation of the patient. The display 125 can depict howthe chosen implants would be installed on the bone if the planned bonecuts are performed. If the surgeon 111 choses to change the previouslyplanned bone cuts, the display 125 can depict how the revised bone cutswould change the position and orientation of the implant when installedon the bone.

The display 125 can provide the surgeon 111 with a variety of data andinformation about the patient, the planned surgical intervention, andthe implants. Various patient-specific information can be displayed,including real-time data concerning the patient's health such as heartrate, blood pressure, etc. The display 125 can also include informationabout the anatomy of the surgical target region including the locationof landmarks, the current state of the anatomy (e.g., whether anyresections have been made, the depth and angles of planned and executedbone cuts), and future states of the anatomy as the surgical planprogresses. The display 125 can also provide or depict additionalinformation about the surgical target region. For a TKA, the display 125can provide information about the gaps (e.g., gap balancing) between thefemur and tibia and how such gaps will change if the planned surgicalplan is carried out. For a TKA, the display 125 can provide additionalrelevant information about the knee joint such as data about the joint'stension (e.g., ligament laxity) and information concerning rotation andalignment of the joint. The display 125 can depict how the plannedimplants' locations and positions will affect the patient as the kneejoint is flexed. The display 125 can depict how the use of differentimplants or the use of different sizes of the same implant will affectthe surgical plan and preview how such implants will be positioned onthe bone. The CASS 100 can provide such information for each of theplanned bone resections in a TKA or THA. In a TKA, the CASS 100 canprovide robotic control for one or more of the planned bone resections.For example, the CASS 100 can provide robotic control only for theinitial distal femur cut, and the surgeon 111 can manually perform otherresections (anterior, posterior and chamfer cuts) using conventionalmeans, such as a 4-in-1 cutting guide or jig 105D.

The display 125 can employ different colors to inform the surgeon of thestatus of the surgical plan. For example, un-resected bone can bedisplayed in a first color, resected bone can be displayed in a secondcolor, and planned resections can be displayed in a third color.Implants can be superimposed onto the bone in the display 125, andimplant colors can change or correspond to different types or sizes ofimplants.

The information and options depicted on the display 125 can varydepending on the type of surgical procedure being performed. Further,the surgeon 111 can request or select a particular surgical workflowdisplay that matches or is consistent with his or her surgical planpreferences. For example, for a surgeon 111 who typically performs thetibial cuts before the femoral cuts in a TKA, the display 125 andassociated workflow can be adapted to take this preference into account.The surgeon 111 can also preselect that certain steps be included ordeleted from the standard surgical workflow display. For example, if asurgeon 111 uses resection measurements to finalize an implant plan butdoes not analyze ligament gap balancing when finalizing the implantplan, the surgical workflow display can be organized into modules, andthe surgeon can select which modules to display and the order in whichthe modules are provided based on the surgeon's preferences or thecircumstances of a particular surgery. Modules directed to ligament andgap balancing, for example, can include pre- and post-resectionligament/gap balancing, and the surgeon 111 can select which modules toinclude in their default surgical plan workflow depending on whetherthey perform such ligament and gap balancing before or after (or both)bone resections are performed.

For more specialized display equipment, such as AR HMDs, the SurgicalComputer 150 may provide images, text, etc. using the data formatsupported by the equipment. For example, if the Display 125 is aholography device such as the Microsoft HoloLens™ or Magic Leap One™,the Surgical Computer 150 may use the HoloLens Application ProgramInterface (API) to send commands specifying the position and content ofholograms displayed in the field of view of the Surgeon 111.

In some embodiments, one or more surgical planning models may beincorporated into the CASS 100 and used in the development of thesurgical plans provided to the surgeon 111. The term “surgical planningmodel” refers to software that simulates the biomechanics performance ofanatomy under various scenarios to determine the optimal way to performcutting and other surgical activities. For example, for knee replacementsurgeries, the surgical planning model can measure parameters forfunctional activities, such as deep knee bends, gait, etc., and selectcut locations on the knee to optimize implant placement. One example ofa surgical planning model is the LIFEMOD™ simulation software from SMITHAND NEPHEW, INC. In some embodiments, the Surgical Computer 150 includescomputing architecture that allows full execution of the surgicalplanning model during surgery (e.g., a GPU-based parallel processingenvironment). In other embodiments, the Surgical Computer 150 may beconnected over a network to a remote computer that allows suchexecution, such as a Surgical Data Server 180 (see FIG. 5C). As analternative to full execution of the surgical planning model, in someembodiments, a set of transfer functions are derived that simplify themathematical operations captured by the model into one or more predictorequations. Then, rather than execute the full simulation during surgery,the predictor equations are used. Further details on the use of transferfunctions are described in U.S. Provisional Patent Application No.62/719,415 entitled “Patient Specific Surgical Method and System,” theentirety of which is incorporated herein by reference.

FIG. 5B shows examples of some of the types of data that can be providedto the Surgical Computer 150 from the various components of the CASS100. In some embodiments, the components may stream data to the SurgicalComputer 150 in real-time or near real-time during surgery. In otherembodiments, the components may queue data and send it to the SurgicalComputer 150 at set intervals (e.g., every second). Data may becommunicated using any format known in the art. Thus, in someembodiments, the components all transmit data to the Surgical Computer150 in a common format. In other embodiments, each component may use adifferent data format, and the Surgical Computer 150 is configured withone or more software applications that enable translation of the data.

In general, the Surgical Computer 150 may serve as the central pointwhere CASS data is collected. The exact content of the data will varydepending on the source. For example, each component of the EffectorPlatform 105 provides a measured position to the Surgical Computer 150.Thus, by comparing the measured position to a position originallyspecified by the Surgical Computer 150 (see FIG. 5B), the SurgicalComputer can identify deviations that take place during surgery.

The Resection Equipment 110 can send various types of data to theSurgical Computer 150 depending on the type of equipment used. Exampledata types that may be sent include the measured torque, audiosignatures, and measured displacement values. Similarly, the TrackingTechnology 115 can provide different types of data depending on thetracking methodology employed. Example tracking data types includeposition values for tracked items (e.g., anatomy, tools, etc.),ultrasound images, and surface or landmark collection points or axes.The Tissue Navigation System 120 provides the Surgical Computer 150 withanatomic locations, shapes, etc. as the system operates.

Although the Display 125 generally is used for outputting data forpresentation to the user, it may also provide data to the SurgicalComputer 150. For example, for embodiments where a monitor is used aspart of the Display 125, the Surgeon 111 may interact with a GUI toprovide inputs which are sent to the Surgical Computer 150 for furtherprocessing. For AR applications, the measured position and displacementof the HMD may be sent to the Surgical Computer 150 so that it canupdate the presented view as needed.

During the post-operative phase of the episode of care, various types ofdata can be collected to quantify the overall improvement ordeterioration in the patient's condition as a result of the surgery. Thedata can take the form of, for example, self-reported informationreported by patients via questionnaires. For example, in the context ofa knee replacement surgery, functional status can be measured with anOxford Knee Score questionnaire, and the post-operative quality of lifecan be measured with a EQSD-5L questionnaire. Other examples in thecontext of a hip replacement surgery may include the Oxford Hip Score,Harris Hip Score, and WOMAC (Western Ontario and McMaster UniversitiesOsteoarthritis index). Such questionnaires can be administered, forexample, by a healthcare professional directly in a clinical setting orusing a mobile app that allows the patient to respond to questionsdirectly. In some embodiments, the patient may be outfitted with one ormore wearable devices that collect data relevant to the surgery. Forexample, following a knee surgery, the patient may be outfitted with aknee brace that includes sensors that monitor knee positioning,flexibility, etc. This information can be collected and transferred tothe patient's mobile device for review by the surgeon to evaluate theoutcome of the surgery and address any issues. In some embodiments, oneor more cameras can capture and record the motion of a patient's bodysegments during specified activities postoperatively. This motioncapture can be compared to a biomechanics model to better understand thefunctionality of the patient's joints and better predict progress inrecovery and identify any possible revisions that may be needed.

The post-operative stage of the episode of care can continue over theentire life of a patient. For example, in some embodiments, the SurgicalComputer 150 or other components comprising the CASS 100 can continue toreceive and collect data relevant to a surgical procedure after theprocedure has been performed. This data may include, for example,images, answers to questions, “normal” patient data (e.g., blood type,blood pressure, conditions, medications, etc.), biometric data (e.g.,gait, etc.), and objective and subjective data about specific issues(e.g., knee or hip joint pain). This data may be explicitly provided tothe Surgical Computer 150 or other CASS component by the patient or thepatient's physician(s). Alternatively or additionally, the SurgicalComputer 150 or other CASS component can monitor the patient's EMR andretrieve relevant information as it becomes available. This longitudinalview of the patient's recovery allows the Surgical Computer 150 or otherCASS component to provide a more objective analysis of the patient'soutcome to measure and track success or lack of success for a givenprocedure. For example, a condition experienced by a patient long afterthe surgical procedure can be linked back to the surgery through aregression analysis of various data items collected during the episodeof care. This analysis can be further enhanced by performing theanalysis on groups of patients that had similar procedures and/or havesimilar anatomies.

In some embodiments, data is collected at a central location to providefor easier analysis and use. Data can be manually collected from variousCASS components in some instances. For example, a portable storagedevice (e.g., USB stick) can be attached to the Surgical Computer 150into order to retrieve data collected during surgery. The data can thenbe transferred, for example, via a desktop computer to the centralizedstorage. Alternatively, in some embodiments, the Surgical Computer 150is connected directly to the centralized storage via a Network 175 asshown in FIG. 5C.

FIG. 5C illustrates a “cloud-based” implementation in which the SurgicalComputer 150 is connected to a Surgical Data Server 180 via a Network175. This Network 175 may be, for example, a private intranet or theInternet. In addition to the data from the Surgical Computer 150, othersources can transfer relevant data to the Surgical Data Server 180. Theexample of FIG. 5C shows 3 additional data sources: the Patient 160,Healthcare Professional(s) 165, and an EMR Database 170. Thus, thePatient 160 can send pre-operative and post-operative data to theSurgical Data Server 180, for example, using a mobile app. TheHealthcare Professional(s) 165 includes the surgeon and his or her staffas well as any other professionals working with Patient 160 (e.g., apersonal physician, a rehabilitation specialist, etc.). It should alsobe noted that the EMR Database 170 may be used for both pre-operativeand post-operative data. For example, assuming that the Patient 160 hasgiven adequate permissions, the Surgical Data Server 180 may collect theEMR of the Patient pre-surgery. Then, the Surgical Data Server 180 maycontinue to monitor the EMR for any updates post-surgery.

At the Surgical Data Server 180, an Episode of Care Database 185 is usedto store the various data collected over a patient's episode of care.The Episode of Care Database 185 may be implemented using any techniqueknown in the art. For example, in some embodiments, a SQL-based databasemay be used where all of the various data items are structured in amanner that allows them to be readily incorporated in two SQL'scollection of rows and columns. However, in other embodiments a No-SQLdatabase may be employed to allow for unstructured data, while providingthe ability to rapidly process and respond to queries. As is understoodin the art, the term “No-SQL” is used to define a class of data storesthat are non-relational in their design. Various types of No-SQLdatabases may generally be grouped according to their underlying datamodel. These groupings may include databases that use column-based datamodels (e.g., Cassandra), document-based data models (e.g., MongoDB),key-value based data models (e.g., Redis), and/or graph-based datamodels (e.g., Allego). Any type of No-SQL database may be used toimplement the various embodiments described herein and, in someembodiments, the different types of databases may support the Episode ofCare Database 185.

Data can be transferred between the various data sources and theSurgical Data Server 180 using any data format and transfer techniqueknown in the art. It should be noted that the architecture shown in FIG.5C allows transmission from the data source to the Surgical Data Server180, as well as retrieval of data from the Surgical Data Server 180 bythe data sources. For example, as explained in detail below, in someembodiments, the Surgical Computer 150 may use data from past surgeries,machine learning models, etc. to help guide the surgical procedure.

In some embodiments, the Surgical Computer 150 or the Surgical DataServer 180 may execute a de-identification process to ensure that datastored in the Episode of Care Database 185 meets Health InsurancePortability and Accountability Act (HIPAA) standards or otherrequirements mandated by law. HIPAA provides a list of certainidentifiers that must be removed from data during de-identification. Theaforementioned de-identification process can scan for these identifiersin data that is transferred to the Episode of Care Database 185 forstorage. For example, in one embodiment, the Surgical Computer 150executes the de-identification process just prior to initiating transferof a particular data item or set of data items to the Surgical DataServer 180. In some embodiments, a unique identifier is assigned to datafrom a particular episode of care to allow for re-identification of thedata if necessary.

Although FIGS. 5A-5C discuss data collection in the context of a singleepisode of care, it should be understood that the general concept can beextended to data collection from multiple episodes of care. For example,surgical data may be collected over an entire episode of care each timea surgery is performed with the CASS 100 and stored at the SurgicalComputer 150 or at the Surgical Data Server 180. As explained in furtherdetail below, a robust database of episode of care data allows thegeneration of optimized values, measurements, distances, or otherparameters and other recommendations related to the surgical procedure.In some embodiments, the various datasets are indexed in the database orother storage medium in a manner that allows for rapid retrieval ofrelevant information during the surgical procedure. For example, in oneembodiment, a patient-centric set of indices may be used so that datapertaining to a particular patient or a set of patients similar to aparticular patient can be readily extracted. This concept can besimilarly applied to surgeons, implant characteristics, CASS componentversions, etc.

Further details of the management of episode of care data is describedin U.S. Patent Application No. 62/783,858 filed Dec. 21, 2018 andentitled “Methods and Systems for Providing an Episode of Care,” theentirety of which is incorporated herein by reference.

Open Versus Closed Digital Ecosystems

In some embodiments, the CASS 100 is designed to operate as aself-contained or “closed” digital ecosystem. Each component of the CASS100 is specifically designed to be used in the closed ecosystem, anddata is generally not accessible to devices outside of the digitalecosystem. For example, in some embodiments, each component includessoftware or firmware that implements proprietary protocols foractivities such as communication, storage, security, etc. The concept ofa closed digital ecosystem may be desirable for a company that wants tocontrol all components of the CASS 100 to ensure that certaincompatibility, security, and reliability standards are met. For example,the CASS 100 can be designed such that a new component cannot be usedwith the CASS unless it is certified by the company.

In other embodiments, the CASS 100 is designed to operate as an “open”digital ecosystem. In these embodiments, components may be produced by avariety of different companies according to standards for activities,such as communication, storage, and security. Thus, by using thesestandards, any company can freely build an independent, compliantcomponent of the CASS platform. Data may be transferred betweencomponents using publicly available application programming interfaces(APIs) and open, shareable data formats.

To illustrate one type of recommendation that may be performed with theCASS 100, a technique for optimizing surgical parameters is disclosedbelow. The term “optimization” in this context means selection ofparameters that are optimal based on certain specified criteria. In anextreme case, optimization can refer to selecting optimal parameter(s)based on data from the entire episode of care, including anypre-operative data, the state of CASS data at a given point in time, andpost-operative goals. Moreover, optimization may be performed usinghistorical data, such as data generated during past surgeries involving,for example, the same surgeon, past patients with physicalcharacteristics similar to the current patient, or the like.

The optimized parameters may depend on the portion of the patient'sanatomy to be operated on. For example, for knee surgeries, the surgicalparameters may include positioning information for the femoral andtibial component including, without limitation, rotational alignment(e.g., varus/valgus rotation, external rotation, flexion rotation forthe femoral component, posterior slope of the tibial component),resection depths (e.g., varus knee, valgus knee), and implant type, sizeand position. The positioning information may further include surgicalparameters for the combined implant, such as overall limb alignment,combined tibiofemoral hyperextension, and combined tibiofemoralresection. Additional examples of parameters that could be optimized fora given TKA femoral implant by the CASS 100 include the following:

Exemplary Parameter Reference Recommendation (s) Size Posterior Thelargest sized implant that does not overhang medial/lateral bone edgesor overhang the anterior femur. A size that does not result inoverstuffing the patella femoral joint Implant Position - Medial/lateralcortical Center the implant Medial Lateral bone edges evenly between themedial/lateral cortical bone edges Resection Depth - Distal andposterior 6 mm of bone Varus Knee lateral Resection Depth - Distal andposterior 7 mm of bone Valgus Knee medial Rotation - Mechanical Axis 1°varus Varus/Valgus Rotation - External Transepicondylar 1° external fromthe Axis transepicondylar axis Rotation - Flexion Mechanical Axis 3°flexed

Additional examples of parameters that could be optimized for a givenTKA tibial implant by the CASS 100 include the following:

Exemplary Parameter Reference Recommendation (s) Size Posterior Thelargest sized implant that does not overhang the medial, lateral,anterior, and posterior tibial edges Implant Position Medial/lateral andCenter the implant anterior/posterior evenly between the cortical boneedges medial/lateral and anterior/posterior cortical bone edgesResection Depth - Lateral/Medial 4 mm of bone Varus Knee ResectionDepth - Lateral/Medial 5 mm of bone Valgus Knee Rotation - MechanicalAxis 1° valgus Varus/Valgus Rotation - External Tibial Anterior 1°external from the Posterior Axis tibial anterior paxis Posterior SlopeMechanical Axis 3° posterior slope

For hip surgeries, the surgical parameters may comprise femoral neckresection location and angle, cup inclination angle, cup anteversionangle, cup depth, femoral stem design, femoral stem size, fit of thefemoral stem within the canal, femoral offset, leg length, and femoralversion of the implant.

Shoulder parameters may include, without limitation, humeral resectiondepth/angle, humeral stem version, humeral offset, glenoid version andinclination, as well as reverse shoulder parameters such as humeralresection depth/angle, humeral stem version, Glenoid tilt/version,glenosphere orientation, glenosphere offset and offset direction.

Various conventional techniques exist for optimizing surgicalparameters. However, these techniques are typically computationallyintensive and, thus, parameters often need to be determinedpre-operatively. As a result, the surgeon is limited in his or herability to make modifications to optimized parameters based on issuesthat may arise during surgery. Moreover, conventional optimizationtechniques typically operate in a “black box” manner with little or noexplanation regarding recommended parameter values. Thus, if the surgeondecides to deviate from a recommended parameter value, the surgeontypically does so without a full understanding of the effect of thatdeviation on the rest of the surgical workflow, or the impact of thedeviation on the patient's post-surgery quality of life.

Operative Patient Care System

The general concepts of optimization may be extended to the entireepisode of care using an Operative Patient Care System 620 that uses thesurgical data, and other data from the Patient 605 and HealthcareProfessionals 630 to optimize outcomes and patient satisfaction asdepicted in FIG. 6.

Conventionally, pre-operative diagnosis, pre-operative surgicalplanning, intra-operative execution of a prescribed plan, andpost-operative management of total joint arthroplasty are based onindividual experience, published literature, and training knowledgebases of surgeons (ultimately, tribal knowledge of individual surgeonsand their ‘network’ of peers and journal publications) and their nativeability to make accurate intra-operative tactile discernment of“balance” and accurate manual execution of planar resections usingguides and visual cues. This existing knowledge base and execution islimited with respect to the outcomes optimization offered to patientsneeding care. For example, limits exist with respect to accuratelydiagnosing a patient to the proper, least-invasive prescribed care;aligning dynamic patient, healthcare economic, and surgeon preferenceswith patient-desired outcomes; executing a surgical plan resulting inproper bone alignment and balance, etc.; and receiving data fromdisconnected sources having different biases that are difficult toreconcile into a holistic patient framework. Accordingly, a data-driventool that more accurately models anatomical response and guides thesurgical plan can improve the existing approach.

The Operative Patient Care System 620 is designed to utilize patientspecific data, surgeon data, healthcare facility data, and historicaloutcome data to develop an algorithm that suggests or recommends anoptimal overall treatment plan for the patient's entire episode of care(preoperative, operative, and postoperative) based on a desired clinicaloutcome. For example, in one embodiment, the Operative Patient CareSystem 620 tracks adherence to the suggested or recommended plan, andadapts the plan based on patient/care provider performance. Once thesurgical treatment plan is complete, collected data is logged by theOperative Patient Care System 620 in a historical database. Thisdatabase is accessible for future patients and the development of futuretreatment plans. In addition to utilizing statistical and mathematicalmodels, simulation tools (e.g., LIFEMOD®) can be used to simulateoutcomes, alignment, kinematics, etc. based on a preliminary or proposedsurgical plan, and reconfigure the preliminary or proposed plan toachieve desired or optimal results according to a patient's profile or asurgeon's preferences. The Operative Patient Care System 620 ensuresthat each patient is receiving personalized surgical and rehabilitativecare, thereby improving the chance of successful clinical outcomes andlessening the economic burden on the facility associated with near-termrevision.

In some embodiments, the Operative Patient Care System 620 employs adata collecting and management method to provide a detailed surgicalcase plan with distinct steps that are monitored and/or executed using aCASS 100. The performance of the user(s) is calculated at the completionof each step and can be used to suggest changes to the subsequent stepsof the case plan. Case plan generation relies on a series of input datathat is stored on a local or cloud-storage database. Input data can berelated to both the current patient undergoing treatment and historicaldata from patients who have received similar treatment(s).

A Patient 605 provides inputs such as Current Patient Data 310 andHistorical Patient Data 615 to the Operative Patient Care System 620.Various methods generally known in the art may be used to gather suchinputs from the Patient 605. For example, in some embodiments, thePatient 605 fills out a paper or digital survey that is parsed by theOperative Patient Care System 620 to extract patient data. In otherembodiments, the Operative Patient Care System 620 may extract patientdata from existing information sources, such as electronic medicalrecords (EMRs), health history files, and payer/provider historicalfiles. In still other embodiments, the Operative Patient Care System 620may provide an application program interface (API) that allows theexternal data source to push data to the Operative Patient Care System.For example, the Patient 605 may have a mobile phone, wearable device,or other mobile device that collects data (e.g., heart rate, pain ordiscomfort levels, exercise or activity levels, or patient-submittedresponses to the patient's adherence with any number of pre-operativeplan criteria or conditions) and provides that data to the OperativePatient Care System 620. Similarly, the Patient 605 may have a digitalapplication on his or her mobile or wearable device that enables data tobe collected and transmitted to the Operative Patient Care System 620.

Current Patient Data 610 can include, but is not limited to, activitylevel, preexisting conditions, comorbidities, prehab performance, healthand fitness level, pre-operative expectation level (relating tohospital, surgery, and recovery), a Metropolitan Statistical Area (MSA)driven score, genetic background, prior injuries (sports, trauma, etc.),previous joint arthroplasty, previous trauma procedures, previous sportsmedicine procedures, treatment of the contralateral joint or limb, gaitor biomechanical information (back and ankle issues), levels of pain ordiscomfort, care infrastructure information (payer coverage type, homehealth care infrastructure level, etc.), and an indication of theexpected ideal outcome of the procedure.

Historical Patient Data 615 can include, but is not limited to, activitylevel, preexisting conditions, comorbidities, prehab performance, healthand fitness level, pre-operative expectation level (relating tohospital, surgery, and recovery), a MSA driven score, geneticbackground, prior injuries (sports, trauma, etc.), previous jointarthroplasty, previous trauma procedures, previous sports medicineprocedures, treatment of the contralateral joint or limb, gait orbiomechanical information (back and ankle issues), levels or pain ordiscomfort, care infrastructure information (payer coverage type, homehealth care infrastructure level, etc.), expected ideal outcome of theprocedure, actual outcome of the procedure (patient reported outcomes[PROs], survivorship of implants, pain levels, activity levels, etc.),sizes of implants used, position/orientation/alignment of implants used,soft-tissue balance achieved, etc.

Healthcare Professional(s) 630 conducting the procedure or treatment mayprovide various types of data 625 to the Operative Patient Care System620. This Healthcare Professional Data 625 may include, for example, adescription of a known or preferred surgical technique (e.g., CruciateRetaining (CR) vs Posterior Stabilized (PS), up-vs down-sizing,tourniquet vs tourniquet-less, femoral stem style, preferred approachfor THA, etc.), the level of training of the Healthcare Professional(s)630 (e.g., years in practice, fellowship trained, where they trained,whose techniques they emulate), previous success level includinghistorical data (outcomes, patient satisfaction), and the expected idealoutcome with respect to range of motion, days of recovery, andsurvivorship of the device. The Healthcare Professional Data 625 can becaptured, for example, with paper or digital surveys provided to theHealthcare Professional 630, via inputs to a mobile application by theHealthcare Professional, or by extracting relevant data from EMRs. Inaddition, the CASS 100 may provide data such as profile data (e.g., aPatient Specific Knee Instrument Profile) or historical logs describinguse of the CASS during surgery.

Information pertaining to the facility where the procedure or treatmentwill be conducted may be included in the input data. This data caninclude, without limitation, the following: Ambulatory Surgery Center(ASC) vs hospital, facility trauma level, Comprehensive Care for JointReplacement Program (CJR) or bundle candidacy, a MSA driven score,community vs metro, academic vs non-academic, postoperative networkaccess (Skilled Nursing Facility [SNF] only, Home Health, etc.),availability of medical professionals, implant availability, andavailability of surgical equipment.

These facility inputs can be captured by, for example and withoutlimitation, Surveys (Paper/Digital), Surgery Scheduling Tools (e.g.,apps, Websites, Electronic Medical Records [EMRs], etc.), Databases ofHospital Information (on the Internet), etc. Input data relating to theassociated healthcare economy including, but not limited to, thesocioeconomic profile of the patient, the expected level ofreimbursement the patient will receive, and if the treatment is patientspecific may also be captured.

These healthcare economic inputs can be captured by, for example andwithout limitation, Surveys (Paper/Digital), Direct Payer Information,Databases of Socioeconomic status (on the Internet with zip code), etc.Finally, data derived from simulation of the procedure is captured.Simulation inputs include implant size, position, and orientation.Simulation can be conducted with custom or commercially availableanatomical modeling software programs (e.g., LIFEMOD®, AnyBody, orOpenSIM). It is noted that the data inputs described above may not beavailable for every patient, and the treatment plan will be generatedusing the data that is available.

Prior to surgery, the Patient Data 610, 615 and Healthcare ProfessionalData 625 may be captured and stored in a cloud-based or online database(e.g., the Surgical Data Server 180 shown in FIG. 5C). Informationrelevant to the procedure is supplied to a computing system via wirelessdata transfer or manually with the use of portable media storage. Thecomputing system is configured to generate a case plan for use with aCASS 100. Case plan generation will be described hereinafter. It isnoted that the system has access to historical data from previouspatients undergoing treatment, including implant size, placement, andorientation as generated by a computer-assisted, patient-specific kneeinstrument (PSKI) selection system, or automatically by the CASS 100itself. To achieve this, case log data is uploaded to the historicaldatabase by a surgical sales rep or case engineer using an onlineportal. In some embodiments, data transfer to the online database iswireless and automated.

Historical data sets from the online database are used as inputs to amachine learning model such as, for example, a recurrent neural network(RNN) or other form of artificial neural network. As is generallyunderstood in the art, an artificial neural network functions similar toa biologic neural network and is comprised of a series of nodes andconnections. The machine learning model is trained to predict one ormore values based on the input data. For the sections that follow, it isassumed that the machine learning model is trained to generate predictorequations. These predictor equations may be optimized to determine theoptimal size, position, and orientation of the implants to achieve thebest outcome or satisfaction level.

Once the procedure is complete, all patient data and available outcomedata, including the implant size, position and orientation determined bythe CASS 100, are collected and stored in the historical database. Anysubsequent calculation of the target equation via the RNN will includethe data from the previous patient in this manner, allowing forcontinuous improvement of the system.

In addition to, or as an alternative to determining implant positioning,in some embodiments, the predictor equation and associated optimizationcan be used to generate the resection planes for use with a PSKI system.When used with a PSKI system, the predictor equation computation andoptimization are completed prior to surgery. Patient anatomy isestimated using medical image data (x-ray, CT, MRI). Global optimizationof the predictor equation can provide an ideal size and position of theimplant components. Boolean intersection of the implant components andpatient anatomy is defined as the resection volume. PSKI can be producedto remove the optimized resection envelope. In this embodiment, thesurgeon cannot alter the surgical plan intraoperatively.

The surgeon may choose to alter the surgical case plan at any time priorto or during the procedure. If the surgeon elects to deviate from thesurgical case plan, the altered size, position, and/or orientation ofthe component(s) is locked, and the global optimization is refreshedbased on the new size, position, and/or orientation of the component(s)(using the techniques previously described) to find the new idealposition of the other component(s) and the corresponding resectionsneeded to be performed to achieve the newly optimized size, positionand/or orientation of the component(s). For example, if the surgeondetermines that the size, position and/or orientation of the femoralimplant in a TKA needs to be updated or modified intraoperatively, thefemoral implant position is locked relative to the anatomy, and the newoptimal position of the tibia will be calculated (via globaloptimization) considering the surgeon's changes to the femoral implantsize, position and/or orientation. Furthermore, if the surgical systemused to implement the case plan is robotically assisted (e.g., as withNAVIO® or the MAKO Rio), bone removal and bone morphology during thesurgery can be monitored in real time. If the resections made during theprocedure deviate from the surgical plan, the subsequent placement ofadditional components may be optimized by the processor taking intoaccount the actual resections that have already been made.

FIG. 7A illustrates how the Operative Patient Care System 620 may beadapted for performing case plan matching services. In this example,data is captured relating to the current patient 610 and is compared toall or portions of a historical database of patient data and associatedoutcomes 615. For example, the surgeon may elect to compare the plan forthe current patient against a subset of the historical database. Data inthe historical database can be filtered to include, for example, onlydata sets with favorable outcomes, data sets corresponding to historicalsurgeries of patients with profiles that are the same or similar to thecurrent patient profile, data sets corresponding to a particularsurgeon, data sets corresponding to a particular aspect of the surgicalplan (e.g., only surgeries where a particular ligament is retained), orany other criteria selected by the surgeon or medical professional. If,for example, the current patient data matches or is correlated with thatof a previous patient who experienced a good outcome, the case plan fromthe previous patient can be accessed and adapted or adopted for use withthe current patient. The predictor equation may be used in conjunctionwith an intra-operative algorithm that identifies or determines theactions associated with the case plan. Based on the relevant and/orpreselected information from the historical database, theintra-operative algorithm determines a series of recommended actions forthe surgeon to perform. Each execution of the algorithm produces thenext action in the case plan. If the surgeon performs the action, theresults are evaluated. The results of the surgeon's performing theaction are used to refine and update inputs to the intra-operativealgorithm for generating the next step in the case plan. Once the caseplan has been fully executed all data associated with the case plan,including any deviations performed from the recommended actions by thesurgeon, are stored in the database of historical data. In someembodiments, the system utilizes preoperative, intraoperative, orpostoperative modules in a piecewise fashion, as opposed to the entirecontinuum of care. In other words, caregivers can prescribe anypermutation or combination of treatment modules including the use of asingle module. These concepts are illustrated in FIG. 7B and can beapplied to any type of surgery utilizing the CASS 100.

Surgery Process Display

As noted above with respect to FIGS. 1 and 5A-5C, the various componentsof the CASS 100 generate detailed data records during surgery. The CASS100 can track and record various actions and activities of the surgeonduring each step of the surgery and compare actual activity to thepre-operative or intraoperative surgical plan. In some embodiments, asoftware tool may be employed to process this data into a format wherethe surgery can be effectively “played-back.” For example, in oneembodiment, one or more GUIs may be used that depict all of theinformation presented on the Display 125 during surgery. This can besupplemented with graphs and images that depict the data collected bydifferent tools. For example, a GUI that provides a visual depiction ofthe knee during tissue resection may provide the measured torque anddisplacement of the resection equipment adjacent to the visual depictionto better provide an understanding of any deviations that occurred fromthe planned resection area. The ability to review a playback of thesurgical plan or toggle between different aspects of the actual surgeryvs. the surgical plan could provide benefits to the surgeon and/orsurgical staff, allowing such persons to identify any deficiencies orchallenging aspects of a surgery so that they can be modified in futuresurgeries. Similarly, in academic settings, the aforementioned GUIs canbe used as a teaching tool for training future surgeons and/or surgicalstaff. Additionally, because the data set effectively records manyaspects of the surgeon's activity, it may also be used for other reasons(e.g., legal or compliance reasons) as evidence of correct or incorrectperformance of a particular surgical procedure.

Over time, as more and more surgical data is collected, a rich libraryof data may be acquired that describes surgical procedures performed forvarious types of anatomy (knee, shoulder, hip, etc.) by differentsurgeons for different patients. Moreover, aspects such as implant typeand dimension, patient demographics, etc. can further be used to enhancethe overall dataset. Once the dataset has been established, it may beused to train a machine learning model (e.g., RNN) to make predictionsof how surgery will proceed based on the current state of the CASS 100.

Training of the machine learning model can be performed as follows. Theoverall state of the CASS 100 can be sampled over a plurality of timeperiods for the duration of the surgery. The machine learning model canthen be trained to translate a current state at a first time period to afuture state at a different time period. By analyzing the entire stateof the CASS 100 rather than the individual data items, any causaleffects of interactions between different components of the CASS 100 canbe captured. In some embodiments, a plurality of machine learning modelsmay be used rather than a single model. In some embodiments, the machinelearning model may be trained not only with the state of the CASS 100,but also with patient data (e.g., captured from an EMR) and anidentification of members of the surgical staff. This allows the modelto make predictions with even greater specificity. Moreover, it allowssurgeons to selectively make predictions based only on their ownsurgical experiences if desired.

In some embodiments, predictions or recommendations made by theaforementioned machine learning models can be directly integrated intothe surgical workflow. For example, in some embodiments, the SurgicalComputer 150 may execute the machine learning model in the backgroundmaking predictions or recommendations for upcoming actions or surgicalconditions. A plurality of states can thus be predicted or recommendedfor each period. For example, the Surgical Computer 150 may predict orrecommend the state for the next 5 minutes in 30 second increments.Using this information, the surgeon can utilize a “process display” viewof the surgery that allows visualization of the future state. Forexample, FIG. 7C depicts a series of images that may be displayed to thesurgeon depicting the implant placement interface. The surgeon can cyclethrough these images, for example, by entering a particular time intothe display 125 of the CASS 100 or instructing the system to advance orrewind the display in a specific time increment using a tactile, oral,or other instruction. In one embodiment, the process display can bepresented in the upper portion of the surgeon's field of view in the ARHMD. In some embodiments, the process display can be updated inreal-time. For example, as the surgeon moves resection tools around theplanned resection area, the process display can be updated so that thesurgeon can see how his or her actions are affecting the other aspectsof the surgery.

In some embodiments, rather than simply using the current state of theCASS 100 as an input to the machine learning model, the inputs to themodel may include a planned future state. For example, the surgeon mayindicate that he or she is planning to make a particular bone resectionof the knee joint. This indication may be entered manually into theSurgical Computer 150 or the surgeon may verbally provide theindication. The Surgical Computer 150 can then produce a film stripshowing the predicted effect of the cut on the surgery. Such a filmstrip can depict over specific time increments how the surgery will beaffected, including, for example, changes in the patient's anatomy,changes to implant position and orientation, and changes regardingsurgical intervention and instrumentation, if the contemplated course ofaction were to be performed. A surgeon or medical professional caninvoke or request this type of film strip at any point in the surgery topreview how a contemplated course of action would affect the surgicalplan if the contemplated action were to be carried out.

It should be further noted that, with a sufficiently trained machinelearning model and robotic CASS, various aspects of the surgery can beautomated such that the surgeon only needs to be minimally involved, forexample, by only providing approval for various steps of the surgery.For example, robotic control using arms or other means can be graduallyintegrated into the surgical workflow over time with the surgeon slowlybecoming less and less involved with manual interaction versus robotoperation. The machine learning model in this case can learn whatrobotic commands are required to achieve certain states of theCASS-implemented plan. Eventually, the machine learning model may beused to produce a film strip or similar view or display that predictsand can preview the entire surgery from an initial state. For example,an initial state may be defined that includes the patient information,the surgical plan, implant characteristics, and surgeon preferences.Based on this information, the surgeon could preview an entire surgeryto confirm that the CASS-recommended plan meets the surgeon'sexpectations and/or requirements. Moreover, because the output of themachine learning model is the state of the CASS 100 itself, commands canbe derived to control the components of the CASS to achieve eachpredicted state. In the extreme case, the entire surgery could thus beautomated based on just the initial state information.

Using the Point Probe to Acquire High-Resolution of Key Areas During HipSurgeries

Use of the point probe is described in U.S. patent application Ser. No.14/955,742 entitled “Systems and Methods for Planning and PerformingImage Free Implant Revision Surgery,” the entirety of which isincorporated herein by reference. Briefly, an optically tracked pointprobe may be used to map the actual surface of the target bone thatneeds a new implant. Mapping is performed after removal of the defectiveor worn-out implant, as well as after removal of any diseased orotherwise unwanted bone. A plurality of points is collected on the bonesurfaces by brushing or scraping the entirety of the remaining bone withthe tip of the point probe. This is referred to as tracing or “painting”the bone. The collected points are used to create a three-dimensionalmodel or surface map of the bone surfaces in the computerized planningsystem. The created 3D model of the remaining bone is then used as thebasis for planning the procedure and necessary implant sizes. Analternative technique that uses X-rays to determine a 3D model isdescribed in U.S. Provisional Patent Application No. 62/658,988, filedApr. 17, 2018 and entitled “Three Dimensional Guide with Selective BoneMatching,” the entirety of which is incorporated herein by reference.

For hip applications, the point probe painting can be used to acquirehigh resolution data in key areas such as the acetabular rim andacetabular fossa. This can allow a surgeon to obtain a detailed viewbefore beginning to ream. For example, in one embodiment, the pointprobe may be used to identify the floor (fossa) of the acetabulum. As iswell understood in the art, in hip surgeries, it is important to ensurethat the floor of the acetabulum is not compromised during reaming so asto avoid destruction of the medial wall. If the medial wall wereinadvertently destroyed, the surgery would require the additional stepof bone grafting. With this in mind, the information from the pointprobe can be used to provide operating guidelines to the acetabularreamer during surgical procedures. For example, the acetabular reamermay be configured to provide haptic feedback to the surgeon when he orshe reaches the floor or otherwise deviates from the surgical plan.Alternatively, the CASS 100 may automatically stop the reamer when thefloor is reached or when the reamer is within a threshold distance.

As an additional safeguard, the thickness of the area between theacetabulum and the medial wall could be estimated. For example, once theacetabular rim and acetabular fossa has been painted and registered tothe pre-operative 3D model, the thickness can readily be estimated bycomparing the location of the surface of the acetabulum to the locationof the medial wall. Using this knowledge, the CASS 100 may providealerts or other responses in the event that any surgical activity ispredicted to protrude through the acetabular wall while reaming.

The point probe may also be used to collect high resolution data ofcommon reference points used in orienting the 3D model to the patient.For example, for pelvic plane landmarks like the ASIS and the pubicsymphysis, the surgeon may use the point probe to paint the bone torepresent a true pelvic plane. Given a more complete view of theselandmarks, the registration software has more information to orient the3D model.

The point probe may also be used to collect high-resolution datadescribing the proximal femoral reference point that could be used toincrease the accuracy of implant placement. For example, therelationship between the tip of the Greater Trochanter (GT) and thecenter of the femoral head is commonly used as reference point to alignthe femoral component during hip arthroplasty. The alignment is highlydependent on proper location of the GT; thus, in some embodiments, thepoint probe is used to paint the GT to provide a high resolution view ofthe area. Similarly, in some embodiments, it may be useful to have ahigh-resolution view of the Lesser Trochanter (LT). For example, duringhip arthroplasty, the Dorr Classification helps to select a stem thatwill maximize the ability of achieving a press-fit during surgery toprevent micromotion of femoral components post-surgery and ensureoptimal bony ingrowth. As is generated understood in the art, the DonClassification measures the ratio between the canal width at the LT andthe canal width 10 cm below the LT. The accuracy of the classificationis highly dependent on the correct location of the relevant anatomy.Thus, it may be advantageous to paint the LT to provide ahigh-resolution view of the area.

In some embodiments, the point probe is used to paint the femoral neckto provide high-resolution data that allows the surgeon to betterunderstand where to make the neck cut. The navigation system can thenguide the surgeon as they perform the neck cut. For example, asunderstood in the art, the femoral neck angle is measured by placing oneline down the center of the femoral shaft and a second line down thecenter of the femoral neck. Thus, a high-resolution view of the femoralneck (and possibly the femoral shaft as well) would provide a moreaccurate calculation of the femoral neck angle.

High-resolution femoral head neck data could also be used for anavigated resurfacing procedure where the software/hardware aids thesurgeon in preparing the proximal femur and placing the femoralcomponent. As is generally understood in the art, during hipresurfacing, the femoral head and neck are not removed; rather, the headis trimmed and capped with a smooth metal covering. In this case, itwould be advantageous for the surgeon to paint the femoral head and capso that an accurate assessment of their respective geometries can beunderstood and used to guide trimming and placement of the femoralcomponent.

Registration of Pre-Operative Data to Patient Anatomy Using the PointProbe

As noted above, in some embodiments, a 3D model is developed during thepre-operative stage based on 2D or 3D images of the anatomical area ofinterest. In such embodiments, registration between the 3D model and thesurgical site is performed prior to the surgical procedure. Theregistered 3D model may be used to track and measure the patient'sanatomy and surgical tools intraoperatively.

During the surgical procedure, landmarks are acquired to facilitateregistration of this pre-operative 3D model to the patient's anatomy.For knee procedures, these points could comprise the femoral headcenter, distal femoral axis point, medial and lateral epicondyles,medial and lateral malleolus, proximal tibial mechanical axis point, andtibial A/P direction. For hip procedures these points could comprise theanterior superior iliac spine (ASIS), the pubic symphysis, points alongthe acetabular rim and within the hemisphere, the greater trochanter(GT), and the lesser trochanter (LT).

In a revision surgery, the surgeon may paint certain areas that containanatomical defects to allow for better visualization and navigation ofimplant insertion. These defects can be identified based on analysis ofthe pre-operative images. For example, in one embodiment, eachpre-operative image is compared to a library of images showing “healthy”anatomy (i.e., without defects). Any significant deviations between thepatient's images and the healthy images can be flagged as a potentialdefect. Then, during surgery, the surgeon can be warned of the possibledefect via a visual alert on the display 125 of the CASS 100. Thesurgeon can then paint the area to provide further detail regarding thepotential defect to the Surgical Computer 150.

In some embodiments, the surgeon may use a non-contact method forregistration of bony anatomy intra-incision. For example, in oneembodiment, laser scanning is employed for registration. A laser stripeis projected over the anatomical area of interest and the heightvariations of the area are detected as changes in the line. Othernon-contact optical methods, such as white light inferometry orultrasound, may alternatively be used for surface height measurement orto register the anatomy. For example, ultrasound technology may bebeneficial where there is soft tissue between the registration point andthe bone being registered (e.g., ASIS, pubic symphysis in hipsurgeries), thereby providing for a more accurate definition of anatomicplanes.

As described herein, some embodiments of the present disclosure areparticularly well adapted for surgical procedures that utilize surgicalnavigation systems, such as the NAVIO surgical navigation system, thatuse optical tracking of patient anatomy and tools in the surgicaltheatre. Such procedures can include knee replacement and/or revisionsurgery, as well as shoulder and hip surgeries.

Some embodiments of the present disclosure are well-suited for use withhandheld surgical tools that have a position and orientation (which canbe called a pose) that is tracked and modeled relative to sensors (e.g.,optical sensors, cameras, position encoders, RF/microwave/laser distancemeasurement, etc.) Such tools can be adapted to be held by a surgeon'shand or by a robotic arm, in various embodiments. In some embodimentsthat utilize a robotic arm to hold the tool, position and orientation ofthe tool can be determined from sensors, such as position encoders, thatdetect the real-time geometry of the robotic arm. As used herein, theterm tool or handpiece can refer to a tool that can be held by surgeonor to a tool that can be held or mounted to or integrated with a roboticarm. While many embodiments may provide the most benefit to handheldtools, embodiments are not intended to be limited to handheld toolsunless noted.

Embodiments of the invention utilize a tool with at least two degrees offreedom for manipulating a tool tip relative to a tool body, where thesedegrees of freedom are controlled by a processor of a surgical system.In some embodiments, the tool is a handheld (or robotically held) devicewith fiducial marks to allow optical tracking of the position andorientation of the tool body relative to patient anatomy. In someembodiments, other conventional sensor means can be used to trackposition and orientation. By tracking the position of the tool bodyrelative to patient anatomy, a processor can control the position of thetooltip relative to the tool body, and by extension relative to patientanatomy, to provide processor control of the tooltip. This can allowsmoother, refined cutting with a tooltip, even when the tool body isused in a freehand manner or by a robotic arm that lacks precisecontrol. The processor can track the tool body and adjust the degrees offreedom to adjust to the position of the cutting tip relative to thepatient anatomy based on the position and orientation of the handhelddevice.

By utilizing processor control of the tooltip relative to the tool body,a processor can define a cutting plane. The plane can be identified in asurgical plan based on preoperative imaging or intraoperativemeasurements. The plane can be selected based on an implant geometry fora knee or hip partial or total arthroplasty. In embodiments that utilizetwo degrees of freedom, an axis of the tool tip can be defined with anoffset position and orientation in one dimension. If a tool body is heldin roughly the same vertical or horizontal orientation (with a slowdrift of up to several degrees, such as +/−40 degrees in someembodiments) during a cut, two degrees of freedom are sufficient toapproximately maintain the tooltip in a cutting plane. This allows asurgeon or robotic arm to hold the tool and move it generally in thedirection of the cutting plane while a processor provides real-timecontrol to maintain the tooltip in the desired cutting plane withprecision, providing a smoother, straighter/flatter, and more consistentcut than could be achieved with a freehand cut. This planar cut willgenerally be sufficient to directly interface with an implant withminimal post-cut surface preparation.

In addition to using two degrees of freedom to maintain the cutting tipin line with a predetermined cutting plane, processor control of therotational speed of the cutting tip can be used to allow the processorto control the extent of the cut in that cutting plane. For example, asan operator moves the cutting tip along the cutting plane near the edgeof the prescribed cut (according to the surgical plan) the processor canslow down the tip rotational speed to give finer control as the operatorapproaches the edge of the cut. Similarly, the processor can stop therotation of the tip as the operator moves to the predetermined end ofthe cut. The terminal edges of the cut in the cutting plane can bethought of as the intersection of two generally orthogonal planes.

An exemplary tool for use with embodiments is a rotary cutting tool thatcuts perpendicular to the axis of an elongated cutting tooltip. Thisrotary cutting tool can be a surgical burr or a linear, sharpened flutedcutting bit, such as a helically cut milling bit. This allows severalmillimeters or more of cutting length along the axis of thecutting/burring tooltip. A fluted cutting bit can give a smooth cut whenthe cutting bit is maintained in a predetermined cutting plane. Theentire cutting surface can be considered the cutting tip, and theprocessor seeks to control the position of this cutting surface toensure it stays within a predetermined cutting plane. Two or moredegrees of freedom can be used to adjust the position of the axis of thecutting tool relative to an axis of the tool body and the angle betweenthese two axes. More than two degrees of freedom can allow control ofother positional offsets (e.g. in lateral or transverse directions) aswell as the angle between the axis of the tooltip and other axes of thetool body (e.g. a lateral or transverse axis). It will be appreciatedthat the number of degrees of freedom can be chosen to balancecomplexity and cost with precision and control of the position and theorientation of the tooltip relative to the tool body.

In the example where two degrees of freedom are used, these degrees maybe presented as linear extension or contraction devices (actuators)running parallel to an axis of the tool body and roughly perpendicularto the axis of the tooltip. These actuators can be coupled betweenpoints in the tool body and points on a motor carriage/housing thatmaintains the angle of the tool tip and provides rotational force ondemand. By extending or contracting these devices along the tool bodyaxis, the position of the axis of the tooltip along the axis of the toolbody as well as of the angle between these two axes can be manipulatedunder processor control. This allows the axis of the tooltip to bemanipulated to always lie along a virtual cutting plane whenever theaxis of the tool body is roughly aligned (within several degrees) withthe normal axis of the plane. The operator can deviate from this normalaxis by several degrees in any direction and the manipulation of thedegrees of freedom can counteract the difference between the tool bodyaxis and the normal axis of the plane. When using only two degrees offreedom, it should be noted, that the tooltip axis may not always bemaintained in the same orientation within that plane, but the tool tipcan be maintained in a direction that is parallel to the two-dimensionalplane. For a planar cut, the tool orientation within that plane isgenerally unimportant to maintaining a smooth, flat cut with a rotarytool, except near boundaries. Thus, real-time control of the offset andorientation of the tooltip relative to the axis of the tool body cancompensate for any deviations in the position and orientation of thetool body relative to the virtual cutting plane, within several degreesof deviation. This can allow aberrant motion of a surgeon's hand orrobotic arm without compromising the ability of the tooltip to cut alongthe virtual cut plane with a smooth and straight cut, provided anyaberrant motion of the tool body is not faster than the processor andactuators can compensate for the deviation. The processor can use anysuitable control method, such as a proportional-integral-derivativecontroller (PID), or a machine learning algorithm to predict motion andcompensate for it, to manipulate the tooltip to provide a suitablysmooth and accurate cut.

FIG. 8 shows an exemplary cutting tool 800 for resecting a portion 7 ofa patient bone 6. After a vertical cut, the tool 800 resects the bone 6along a plane in a cutting direction 8. The tool 800 includes a fiducialmarker array 802 affixed to a tool body 804 that facilitates opticaltracking of the position and location of the tool body. A rotary cuttingtooltip 806 cuts perpendicular to its axis as it moves along the cuttingdirection 8. Internal actuators provide degrees of freedom to move theposition and vertical orientation of the cutting tooltip 806 relative tothe tool body 804.

In some embodiments, the tooltip 806 extends from the tool body 804 at adepth that is less than the total depth of the patient bone 6. In suchembodiments, upon completion of the cut in the cutting direction 8, theresected portion 7 will need to be further removed, but the resectedsurface will be flat and smooth. Other surgical tools, such as rasps orosteotomes may be used to complete the resection and flatten any portionof the patient bone 6 that was not cut by the tooltip 806.

In some embodiments, a diameter of the tooltip 806 varies along thelength of the tooltip. For example, the tooltip 806 may be tapereddistally such that a distal portion of the tooltip 806 has a smallerdiameter than a proximal portion of the tooltip 806. The diameters atvarious portions of the tooltip 806 may be selected to control thestiffness and/or required motor torque for cutting and removing bone.For example, a greater diameter at portions of the tooltip 806 mayprovide greater stiffness to the tooltip 806 and a smaller diameter atportions of the tooltip 806 may reduce the necessary motor torque torotate the tooltip 806 and/or the necessary force applied by the surgeonto cut through bone. Accordingly, in some embodiments, diameters at eachportion of the tooltip 806 and/or a slope of a tapered portion of thetooltip 806 may be selected to provide an optimal balance of stiffnessand required motor torque for the tooltip 806. In additionalembodiments, the diameter of the tooltip 806 is constant along thelength of the tooltip 806 and the diameter may be selected to provide anoptimal balance of stiffness and motor torque for the tooltip 806.

In some embodiments, a tool rest or cutting guide 808 is provided aspart of the tool body 804. This cutting guide 808 allows the tool body804 to be in mechanical contact with a surface of the patient bone 6during the cutting operation. As such, the cutting guide 808 can be usedto reduce vibration and deviation from the cutting plane. Furthermore, aprocessor can determine a rough model of the path that the tooltip 806will follow relative to the tool body 804 as the tool is moved in thecutting direction 8 because the necessary distance between the tooltip806 and the cutting guide 808 is largely dictated by the geometry of thecutting plane relative to the surface of the patient bone 6 and anyangular deviation introduced by the robotic arm or surgeon's hand. Theoffset distance between the tooltip 806 and the cutting guide 808 may bepredetermined and/or input to the processor. Accordingly, the processormay predict the path of the tooltip 806 and plan actuation of tooltip tomaintain the tooltip at the cutting plane. For example, a model of thepatient bone 6 may be utilized to identify changes in height (e.g., apeak or a valley) along the upper surface of the patient bone 6. Becausethe cutting guide 808 slides along the upper surface of the patient bone6, the processor may use this information to predict correspondingchanges in the vertical position of the tool 800 and begin to adjust theposition of the tooltip 806 in a predictive manner. For example, theprocessor may begin to adjust the position of the tooltip 806 beforemovement of the tool body 804 is detected by a tracking system. Theprocessor may also utilize a speed and/or vector of movement of the tool800 along the cutting plane to predict the timing of the adjustments tothe position of the tooltip 806. The predictive control of the tooltip806 as described herein may additionally compensate for lag or gaps indetection of the position of the tool 800.

In some embodiments, the cutting guide 808 comprises an arm having aproximal end coupled to the tool body 804 and a distal contact end forcontacting the patient bone 6 (as shown in greater detail in FIG. 9). Insome embodiments, the cutting guide 808 extends from the tool body 804in substantially the same direction as the tooltip 806 such that thecutting guide 808 may contact the surface of the patient bone 6 duringbone resection.

In some embodiments, the cutting guide 808 is configured to contact anupper surface of the patient bone 6 during resection. For example, asshown in FIG. 8, the cutting guide 808 may be located above the tooltip806 to contact an upper surface of the patient bone 6. A proximalportion of the arm may extend substantially parallel to the tooltip 806and a distal portion of the arm may curve downward in the direction ofthe tooltip. However, in some embodiments, the cutting guide 808 may besubstantially straight along its entire length.

Additional shapes and orientations for the cutting guide 808 arecontemplated herein. In some embodiments, the proximal end of thecutting guide 808 may be coupled to another portion of the tool body 804such as a portion to the left of the tooltip 806, a portion to the rightof the tooltip, or a portion below the tooltip. For example, theproximal end of the cutting guide 808 may be coupled to a portion of thetool body 804 that houses the internal actuators, i.e., below thetooltip 806. Accordingly, the cutting guide 808 may be adequately sizedto position the distal contact end above the tooltip 806 to contact theupper surface of the patient bone 6 during resection. The cutting guide808 may include one or more curved portions that extend around and/orover the remainder of the tool body 804 in order to position the distalcontact end of the cutting guide 808 above the tooltip 806.

The overall shape and position of the arm of the cutting guide 808 maybe configured to provide adequate clearance between the cutting guideand the tooltip 806 to prevent interference with positioning of the tool800 during resection. In some embodiments, the arm of the cutting guide808 is adequately spaced from the tooltip 806 along the entire length ofthe cutting guide in order to prevent interference with positioning oftool 800, e.g., due to unintended contact of the cutting guide 808 withthe patient bone 6.

In some embodiments, the distal contact end of the cutting guide 808 isconfigured to slide along the surface of the patient bone 6. In someembodiments, the distal contact end of the cutting guide 808 may beshaped to reduce resistance to sliding movement along the surface of thepatient bone 6. For example, the distal contact end may comprise asphere or a ball (as depicted in FIGS. 8-9) such that the distal contactend may slide along the surface of the patient bone. In someembodiments, the distal contact end may comprise a hemisphere or aportion of a sphere. Spherical shapes may be particular advantageousbecause rotation of the tool 800 (e.g., rotation about the pitch, yaw,and/or roll axes) will not substantially affect the contact with thepatient bone 6. Therefore, the distal contact end may continue to slidealong the surface of the patient bone 6 in substantially the samemanner. In another embodiment, the distal contact end may comprise asubstantially cylindrical shape. Additional or alternative smooth and/orrounded shapes may be implemented at the distal contact end as would beapparent to a person having an ordinary level of skill in the art.

FIG. 9 shows the operation of the tool 800 with active degrees offreedom as the forward pitch of the tool body 804 is changed. As shownin FIG. 9, the tooltip 806 may be rotated to cut in a direction comingout of the page. The surgeon places the cutting guide 808 in contactwith the surface of the patient's condyle or tibial plateau at alocation that allows the tooltip 806 to be manipulated in thepredetermined cutting plane. The location of contact between the cuttingguide 808 and the patient bone 6 also allows the surgeon to control thedepth of the tooltip 806 so that the cut is made in the cutting plane ata depth that allows the tooltip to cut most of the depth of the patientbone, but leave enough bone past the tip to allow the surface of thebone 6 along which the cutting guide 808 rides to remain intactthroughout the entire cutting process.

Within the tool body 804, linear actuators, such as 810 and 812, mayprovide, for example and without limitation, two degrees of freedom tomanipulate the position and pitch of the tooltip 806 relative to thetool body. A sliding pin-and-slot 814 restricts the movement of thecutting tooltip 806 in the axial direction. The linear actuator devices810 and 812 are described as linear actuators, but may include anysuitable device that provides contraction and extension along an axis.In some embodiments, linear actuator devices may include any combinationof linear motors, piezoelectric motors, pneumatic or hydraulicactuators, and gear motors with lead screws attached to the outputshaft. Actuator devices, such as 810 and 812, can be mounted with pinsto a motor housing 816 to allow the actuator devices to push or pull themotor housing without being rigidly coupled. The axis of the motorhousing 816 may be parallel to the axis of the cutting tooltip 806. Amotor within the motor housing 816 rotates the tooltip 806 at an angularvelocity suitable to provide a cutting action in a direction transverseto that axis.

In one example, a surgeon's hand holds a portion of the tool body 804below the motor housing 816 and deviates his hand position towards apatient bone 6 causing the tool body to move in a first direction 817. Aprocessor controlling the linear actuators 810 and 812 may adjust theextension of the actuators to move the tool body 804 to compensate forthe motion and direction 817 in which the tool 800 is moved. In anotherexample, a surgeon's hand moves away from the patient bone 6 with aslight deviation. Such movement may cause the tool body 804 to move in asecond direction 818. The processor controlling the linear actuators 810and 812 may adjust the extension of the actuators to compensate for suchmovement by keeping the axis of the motor housing 816 and the tooltip806 consistent with the cutting plane. For example, actuator 812 maycontract more than actuator 810 (which may need to extend) tocompensate.

FIGS. 10 and 11 illustrates that a tool 800 having only two degrees offreedom can effectively achieve orthogonal cuts. This can beaccomplished using a rotational movement of the tool body 804 during thefirst vertical cut and then holding the tool body in a vertical positionduring a horizontal cut. In this example, the tibial plateau is to bepartially resected using two orthogonal cuts. The workflow uses thevertical cut as the initial cut followed by a cut in the horizontal cutplane. Because the tool only has two degrees of freedom, in thisexample, (allowing the processor to make adjustments in the verticalplane that is defined by the sheet in FIG. 9), the tool should berotated such that the axis of the actuators are somewhat horizontal(e.g., within 40 degrees of being horizontal). Because the cut plane isperpendicular to the axis of the cutting tip, these degrees of freedomallow the vertical cutting plane to be generally perpendicular to theplane of the tool that defines the degrees of freedom. When the cuttingplane is generally perpendicular to the axis of the actuators, thedegrees of freedom give the processor the most control of the cuttingtip. However, because the orientation of the cutting tip within thatcutting plane generally does not matter (except near boundaries), theprocessor can still achieve control of the cutting tip to keep it withinthe cutting plane, even when the tool body is rotated such that theactuators are substantially deviated from being perpendicular to thedirection of travel of the cutting tip (e.g., the bottom of the toolbody can be substantially rotated in or out of the page up to 40+degrees in FIG. 9 and still allow for the actuators to keep the cuttingtip in the cutting plane). This is illustrated in FIG. 10.

To make the vertical cut, the operator places cutting guide 808 incontact with the head of the tibial plateau and holds of the toolroughly perpendicular to the long axis of the bone 6. Once the operatoractivates the cutting tip and engages the patient bone to make thevertical cut, the tool is pushed down and rotated. Because the cuttingguide 808 is engaging the top of the tibial plateau, the vertical cut isnot possible without rotation in this example. However, because the goalof the processor is to maintain the axis of the cutting tip within thevertical plane, and not necessarily hold the axis of the cutting tipperfectly horizontal, the cutting tip can be maintained in the verticalvirtual cut plane even through this rotation with two degrees offreedom. In addition, the processor can control the speed of the cuttingtool to prevent the end or any portion of the cutting tip from cuttingpast the second, horizontal cut plane. Furthermore, because the tool isrotated by the operator as the cut proceeds downward, the tool should becloser to vertical once the cutting tip nears the horizontal virtualcutting plane. This ensures that the degrees of freedom can be used toprevent the cutting tip from crossing that virtual boundary.

In some embodiments, during the vertical cut as the angle of the toolbody is rotated towards the vertical position, the processor canintentionally deviate the cut from the vertical cut plane into theresected area, requiring later cleanup near the boundary between thevertical and horizontal cut plans. This cleanup can be done manuallyusing rasps or osteotomes, as is conventionally done during surgery.This can be useful because as the tool becomes more vertical, thedegrees of freedom are more limited in their ability to maintain thetooltip in the vertical cut plane. In some embodiments, the tooltip spinrate can be reduced by the processor as the tool moves into a morevertical position during this vertical cut to limit the damage thatmight occur while the degrees of freedom have less impact on keeping thecut coincident with the vertical virtual cut plane. In some embodiments,the operator intentionally does not rotate the cutting tool beyond acertain angle, such as 45 degrees, as shown in FIG. 10 during thisvertical cut. This can limit the depth of the vertical cut due to thecutting guide, but ensures that the degrees of freedom have sufficientcontrol over the cutting tip relative to the vertical cutting plane toavoid cutting outside the resection area, crossing either virtual cutplane.

In some embodiments, fiducial markers can be less effective as they arerotated away from the vertical position. As shown in FIG. 10, as thetool is rotated, the fiducial marker array 802 becomes less verticaland, beyond a certain angle, the fiducial marks, with some camerasystems, may be less effective. Therefore, it may be undesirable torotate the tool beyond a certain angle relative to any tracking camerasused in the surgical theater. As shown in FIG. 11, in some embodiments,the fiducial marker array 802 can be rotated manually before startingthe horizontal cut. Encoders or user input may inform a processor of therotation angle of the array, and the tracking system can account for thechange in position of the fiducial marker array 802 relative to the toolbody and cutting tip due to known tool geometry. In some embodiments, amultifaceted fiducial marker array 802 can be used that isthree-dimensional, rather than a two-dimensional plane. This can allowthe tool to operate in various orientations without repositioning thefiducial marker array 802. In some embodiments, the cutting guide 808can also be rotated or removed by an operator to give more flexibilityin the types of cuts possible.

Further, while the fiducial marker array 802 is described as beingcoupled to the tool body 804, the fiducial marker array 802 may bearranged in a variety of manners upon the tool 800. In some embodiments,the fiducial marker array 802 may be coupled to the motor housing 816 ora support thereon as depicted in FIG. 9 and may facilitate opticaltracking of the position and location of the tool 800 and/or the tooltip806 based on a known geometry between the tool body 804, the tooltip806, and/or the motor housing 816. Reducing the number of components inthe kinematic chain between the fiducial marker array 802 and thetooltip 806 in this manner may result in a reduced amount of error inthe calculated position of the tooltip. Additional arrangements andorientations with respect to the tool 800 are contemplated herein aswould be apparent to a person having an ordinary level of skill in theart.

In FIG. 11, the operator has completed the vertical cut and now rotatesthe tool body into a substantially vertical position. This allows thecutting guide to be substantially above the cutting tip and allows thecutting guide 808 to travel along the tibial plateau during thehorizontal cut, providing a stable base for the operator's hand orrobotic arm. During this cut, the tool is maintained in a substantiallyvertical position, ideally not changing the vertical orientation of thetool as it travels horizontally along the cut plane, within theoperator's ability. Angular and vertical positional changes due todeviation in the motion of the surgeon's hand or robotic arm can beaccounted for using the degrees of freedom under processor control. Thisensures that as the operator moves the tool body the cutting tip travelsin substantially the same plane as the virtual horizontal cut plane. Thedegrees of freedom compensate primarily for pitch and vertical positionof the tooltip. Yaw is generally not compensated for, but does notaffect the ability of the tooltip to stay within the horizontal cuttingplane. It is not critical that the cutting tip remain parallel to thesurface of the vertical cut during horizontal cut, except near theboundary of these two planes. Roll of the cutting tool can also becompensated for to the extent it affects the ability of the tooltip tostay within the cutting plane, but roll generally does not affect theability of the rotary cutting tip to perform the cut due to therotational nature of the cutting tool.

FIG. 12 is a top-level system diagram of a surgical system utilizing themulti-degree of freedom tool described herein. The system 1200 includesa processor 1202 that controls the operation of the degrees of freedomand the rotary motor of the tool. The processor 1202 controls thesurgical tool in accordance with a surgical plan that can be stored in anon-transitory memory device 1204. The surgical plan can be apreoperative plan created prior to commencement of the surgery based onsurgeon input and medical imaging, such as MRIs, CAT scans, x-rays,ultrasounds, etc. In some embodiments, the surgical plan can be updatedor modified or created intraoperatively based on surgeon input. Forexample, ultrasound or x-ray information obtained or generated duringsurgery can be used to create or modify a surgical plan. Similarly, asurgeon can modify the surgical plan based on what she sees duringsurgery. For example, once a patient's anatomy is registered with arobotic tracking system, the surgeon may then interact with a model ofthe patient's anatomy on a user interface to create or update thesurgical plan based on the surgeon's expertise and information learnedby interacting with the patient anatomy. This can include moving patientjoints and detecting resistances or strains or by determining the extentof damage once a patient's soft tissue is exposed. This can be usefulfor partial or total hip and knee arthroplasty, as well as any otherjoint surgery. In some embodiments, the processor 1202 automaticallyupdates the surgical plan based on observed/imaged/recorded anatomicalfeatures or geometry and a model of the geometry of the prosthetic beingimplanted.

The processor 1202 is also in communication with a tracking system thatutilizes any suitable tracking means to register and track patientanatomy (e.g. bones or soft tissue) and any relevant surgical tools,such as cutting tools, robotic arms, or surgical personnel. In thisexample, an optical tracking system is used. The tracking system 1206can include one or more optical or IR cameras that record images of thesurgical theater, which may include fiducial markers that have beenregistered to salient features of tools or anatomy. The tracking system1206 processes the images to create a three-dimensional model of therelevant features of the environment. In the example of an opticaltracking system, within the surgical theater a plurality of fiducialmarks 1208 can be affixed to tools and patient anatomy; known geometryor input from surgery personnel can assist the image tracking system1206 with determining the position and orientation of these marks orleads to relevant features, such as bone surfaces and the orientation orimportant geometry of tools being used by personnel.

The processor 1202 utilizes information gleaned from the tracking system1206 to control the tool 800. The tool 800 can include an array or3-dimensional group of fiducial markers 802 to allow the tracking system1206 to model the orientation and position of the tool relative to theenvironment and communicate this information to the processor 1202. Theprocessor 1202 communicates with the tool 800 via a communicationinterface 1214. The communication interface 1214 may communicate withthe processor 1202 wirelessly or through a hardwired connection. In someembodiments, a hardwired connection provides a convenient and reliablemeans to send control and sensor information between the processor 1202and the tool 800, particularly in embodiments in which the tool requiresa power source. In some embodiments, the tool 800 may be a wirelessbattery-powered device and communication can occur wirelessly, such asvia Wi-Fi, Bluetooth, or any other suitable wireless communicationprotocol. The communication interface 1214 receives power from a powersource 1212. The power source 1212 can include a battery or an AC or DCconnection to a central power source of the system 1200. Thecommunication interface 1214 can send control signals responsive to theprocessor 1202 to the degree of freedom (DoF) controllers 1216 thatcontrol the linear actuators 810 and 812. Communication between thefiducial marker array 802, the image tracking system 1206, the processor1202, the communication interface 1214, and the DoF controllers 1216allows the processor to determine the position of the tool body 804 withrespect to the patient's anatomy and to send control signals toactuators within the tool to compensate for deviations in position andorientation to ensure the tooltip 806 travels along the virtual cuttingplane during a cutting operation.

In some embodiments, the communication interface may be used to controlthe power source 1212 and selectively send current to a motor thatcauses the tooltip 806 to rotate. In such embodiments, the speed of therotary tool may be controlled by the processor 1202. In suchembodiments, the processor 1202 may stop the rotary action of thetooltip 806 when the tooltip is in danger of intersecting anothervirtual cut plane or of leaving a prescribed cutting area. Similarly,the processor 1202 may selectively initiate a cutting operation in suchembodiments.

In some embodiments, one or more sensors 1218 may provide additionalinformation to the processor 1202 regarding the state of the cuttingtool 800. For example, the one or more sensors 1218 may include a switchthat allows a surgeon to selectively instruct the processor 1202 tostart the cutting operation. The processor 1202 may control the DoFcontrollers 1216 and selectively provide power to the cutting tooltip806 to perform the cutting operation in accordance with the surgicalplan and the real time location of the cutting tip. The one or moresensors 1218 can also include one or more encoders that provideinformation about the state of the actuators 810 and 812 and the speedof the cutting tooltip 806 to the processor 1202.

FIG. 13 is a flow chart of an exemplary method 1300 for using a surgicalrotary tool, in accordance with some embodiments. At step 1302, asurgical plan is created. This can include a plan generatedautomatically using a machine learning algorithm or through humaninteraction based on 3D (MRI, CT scan, 3D ultrasound) or 2D (x-ray orultrasound) medical imaging. The surgical plan can include a model ofone or more implants and the cutting planes to be used relative to thegeometry of the bone tissue to ensure proper functioning of arthroplastyimplants, such as partial or total knee or hip replacement hardware.

At step 1304, during the surgery, the position tracking system iscalibrated and prepared. This can include mounting fiducial markerarrays to patient bones and registering the location of these fiducialmarker arrays relative to bone joint surfaces, such as by “painting” ajoint surface using a stylus having a fiducial marker array once thefiducial marker arrays of the patient bones are registered to thetracking system. This can also include using a robotic arm to interactwith patient bone surfaces to register those surfaces relative to therobotic arm geometry to create a model of patient anatomy relative toknown positions of features of the robotic arm.

Once the environment is prepared for tracking, at step 1306, the rotarytool is placed in contact with patient bone tissue and resection canbegin. Resection begins by placing the tool cutting guide 808 in contactwith some known surface of patient bone tissue and rotating the rotarycutting tooltip as it engages the patient tissue.

At step 1308, the position of the tool body and the tooltip are trackedrelative to the patient's anatomy. This can include tracking theposition of a robotic arm of known geometry that holds the tool body ofknown geometry and identifying the location of the cutting tip based onthe state of linear actuators that control the position and orientationof the cutting tip. This can also include optically tracking a fiducialmarker array fixed to the tool body and using a model of the geometry ofthe fiducial marker array relative to the tool body and a model of theactuators and by extension location of the tooltip relative to the toolbody. In some embodiments, the tracking system has means of optically ordirectly tracking the orientation of the tooltip.

At step 1310, the processor, in response to tracking the body andtooltip relative to the patient anatomy, controls the rotational speedand degrees of freedom of the tool. This, in turn, controls the cuttinglocation of the tooltip relative to the patient anatomy to compensatefor the position and orientation of the tool body. Speed can becontrolled to make the cut, stop a cut, slow down a cut, etc. In someembodiments, more than two degrees of freedom can be used to addadditional control to a tooltip (i.e., other than ensuring that thetooltip is within a plane that is roughly perpendicular to the main axisof the tool body). For example, the depth of the distal end of thetooltip can be controlled relative to the tool body to increase ordecrease the depth of the cut, lateral degrees of freedom can be used toadjust the relative angle of the tooltip within the plane of the cut toassist the surgeon with precise motion within the cutting plane, or thelike.

At step 1312, the processor determines whether the cut is complete orwhether the tooltip is deviating from the surgical plan such that it isabout to cut into tissue beyond the length of the planned cut (e.g. pastthe intersection of vertical and horizontal cutting plans). If so, theprocessor may reduce the rotational speed of the shaft of the rotarytool and repeat step 1310. If not, the process may continue as thesurgeon or the robotic arm moves the tool along the cutting plane atstep 1314. This may result in cutting the bone tissue in accordance withthe surgical plan in the virtual cutting plane. This cycle may thenrevert to step 1308, repeatedly tracking the tooltip location andcompensating for the position and angle of the tool body and determiningwhether or not the cut is complete as the surgeon moves the tool.

The devices, systems, and methods as described herein are not intendedto be limited in terms of the particular embodiments described, whichare intended only as illustrations of various features. Manymodifications and variations to the devices, systems, and methods can bemade without departing from their spirit and scope, as will be apparentto those skilled in the art.

While the devices, systems, and methods are particularly described forperforming tibial cuts, the devices, systems, and methods may also beutilized for performing femoral cuts. For example, one or more distalfemur cuts, anterior cuts, posterior cuts, and/or chamfer cuts may beperformed by the devices, systems, and methods described herein.

While the tool body 804 is depicted as enclosing the linear actuators810/812 and the motor housing 816, in some embodiments one or morecomponents may be external to the tool body 804. For example, the motorhousing 816 may be external to the tool body 804. In some embodiments,the tool body 804 encloses the linear actuators 810/812 and is sealedoff below the motor housing 816. For example, a flexible material may beused to seal the tool body 804 around the linear actuators 810/812 at aninterface with the motor housing 816. Additional configurations of thetool body 804 are contemplated as would be apparent to a person havingan ordinary level of skill in the art.

In some embodiments, the tool body 804 may further comprise a frontguard to prevent the tool 800 from being advanced towards the patientbone 6 beyond a predetermined distance. For example, the front guard mayextend from the tool body 804 in substantially the same direction as thetooltip 806 (as shown in FIG. 9) to maintain the tool 800 at least at apredetermined distance from the patient bone 6, thereby preventing thetooltip 806 from cutting beyond a planned depth and/or damaging otherportions of the patient anatomy.

In some embodiments, the cutting guide 808 is adjustable to change anoffset distance between the cutting guide and the tooltip 806. Forexample, the offset distance may be adjusted to roughly match a distanceof the virtual cutting plane from the surface of the patient bone 6. Insome cases, adjustment of the cutting guide 808 may be necessary toreach the virtual cutting plane with the tooltip 806 because the linearactuators 810/812 may have a limited ability to vertically repositionthe tooltip.

In some embodiments, a plurality of removable cutting guides 808 may beprovided. In some embodiments, each removable cutting guide 808 isconfigured for a different offset distance from the tooltip 806, and asurgeon may select a cutting guide 808 based on the required offsetdistance. In some embodiments, a proximal end of the cutting guide 808may be threaded and configured to mate with a bore on the tool body 804having corresponding threads to secure the cutting guide to the toolbody. In some embodiments, the cutting guide 808 may be configured tomate with a bore on the tool body 804 by friction or interference fit.Additional manners of mating the cutting guide 808 with the tool body804 are contemplated herein as would be apparent to a person having anordinary level of skill in the art. In some embodiments, the cuttingguide 808 may include indicia associated with the offset distance thatmay be input to the processor. For example, the indicia may indicate theoffset distance as a measurement and/or an indexed number or settingthat corresponds to the known offset distance of each removable cuttingguide 808. The processor may determine the offset distance based on theindicia and utilize the offset distance for controlling the tooltip 806as further described herein.

In some embodiments, the cutting guide 808 forms an adjustable jointwith the tool body 804 for changing the offset distance. For example,the cutting guide 808 may be threaded into the tool body 804 orotherwise axially rotatable (i.e., about a roll axis) with respect tothe tool body. Accordingly, in embodiments in which the cutting guide808 includes one or more curves or bends, rotation of the cutting guidemay result in a change in the offset distance of the distal contact endof the cutting guide from the tooltip 806. Where a plurality ofremovable cutting guides 808 are provided as described herein, theadjustable joint may be utilized to make minor adjustments to the offsetdistance (i.e., fine tuning).

In some embodiments, the cutting guide 808 comprises an adjustable jointalong the arm for changing the offset distance. For example, theadjustable joint may be a hirth joint formed with the tool body 804 orat a point along the arm of the cutting guide 808. Mating portions ofthe hirth joint may include interlocking teeth that are secured togetherby a screw or other fastener to lock the joint. In some embodiments, theoffset distance may be changed by rotating a first mating portion withrespect to a second mating portion about a pitch axis, thereby changingthe pitch of the arm of the cutting guide 808 and rotating the distalcontact end towards or away from the tooltip 806. When an adequateoffset distance is achieved, the mating portions may be locked togetherby the screw. In some embodiments, the adjustable joint may includeindicia associated with the offset distance that may be input to theprocessor as described herein. For example, the indicia may indicate theoffset distance as a measurement and/or an indexed number or settingthat corresponds to a known offset distance based on the position of theadjustable joint. The processor may determine the offset distance basedon the indicia and utilize the offset distance for controlling thetooltip 806 as further described herein.

In some embodiments, the cutting guide 808 may be formed from asemi-rigid material. For example, the cutting guide 808 may be formedfrom a stiff wire. The semi-rigid material may be sufficiently flexibleto be re-shaped under a relatively high force, e.g., forceful bending bya surgeon's hand, and sufficiently rigid to hold the shape againstrelatively low forces, e.g., routine contact forces during a resection.

In some embodiments, the distal contact end of the cutting guide 808 maycomprise a low-friction surface or a low-friction coating thereon toreduce resistance to movement of the distal contact end along thesurface of the patient bone 6.

The cutting guide 808 may be altered in various manners to increase acontact surface with the patient bone to improve stability of the tool800. In some embodiments, a plurality of distal contact ends may beincluded on the cutting guide 808. For example, two or more sphericalballs may extend from the cutting guide 808 (e.g., a fork-shaped cuttingguide) to further stabilize the tool 800 and reduce rotation in anadditional degree of freedom. In some embodiments, the distal contactend may be formed as a plate that is freely rotatable with respect tothe tool body 804. For example, the spherical ball of the cutting guide808 as shown in FIG. 9 may be received within a socket of a plateelement to form a ball and socket joint. The plate element may serve asthe distal contact end and rest on the surface of the patient bone 6 toprovide greater stability to the tool 800.

In some embodiments, the tool rest or cutting guide 808 is providedseparately from the tool body 804. In some embodiments, the cuttingguide 808 is configured to be secured to the patient bone 6 or anotherportion of the patient anatomy such that the tool body 804 and tooltip806 may contact the cutting guide 808 to rest thereon and stabilize thetool 800. For example, the cutting guide 808 may be a rigid element thatmay be secured to the patient anatomy and fixed with respect thereto.The cutting guide 808 may be secured to the patient anatomy byadjustable straps (e.g., one or more straps secured by hook and loopfasteners) or any other means of securement as would be known to aperson having an ordinary level of skill in the art. In someembodiments, the cutting guide 808 includes a flat or substantiallyplanar surface for receiving a portion of the tool body 804 or thetooltip 806. In some embodiments, the tool 800 may rest upon the cuttingguide 808 and may be moved along the planar surface as the cut iscompleted, thereby providing additional stability to the tool 800 and/orrelieving stress on the surgeon's hand during the resection. In someembodiments, the cutting guide 808 may comprise a low-friction surfaceor a low-friction coating thereon to reduce resistance to movement ofthe tool body 804 along the cutting guide.

In one example, the rigid element may be an L-shaped bracket or aU-shaped bracket that forms a ledge for resting and guiding the tool800. The bracket may be strapped to the tibia to perform tibial cutsand/or to the femur to perform femoral cuts. The bracket may havesufficient depth to receive the tool 800 and to allow some movement ofthe tool 800 towards or away from the patient bone 6. In someembodiments, a patient-contacting face of the bracket comprises paddingor foam to conform to the shape of the patient anatomy and reducediscomfort to the patient. In some embodiments, a horizontal surface ofthe bracket may be utilized to guide the tool 800 through the horizontalcut on the tibia. Similarly, a vertical surface of the bracket may beutilized to guide the tool 800 through the vertical cut on the tibia. Insome embodiments, the bracket may also be used to guide the tool 800through horizontal and/or vertical cuts on the femur in a similarmanner. In some embodiments, the bracket may include a guard or backstopto prevent the tool 800 from being advanced towards the patient bone 6beyond a predetermined distance. For example, the guard or backstop maymaintain the tool 800 at least at a predetermined distance from thepatient bone 6, thereby preventing the tooltip 806 from cutting beyond aplanned depth and/or damaging other portions of the patient anatomy.

In some embodiments, the bracket may be used to guide the tool 800through chamfer cuts on the femur. Because the chamfer cuts may beangled with respect to the longitudinal axis of the patient bone (e.g.,approximately 45°), the bracket and/or the patient bone may berepositioned to provide an appropriately angled ledge for the tool 800.For example, the bracket may be strapped to the tibia and the knee jointmay be flexed to position the femur at an appropriate angle with thebracket. In another example, the bracket (e.g., an L-shaped bracket) maybe rotated 45° and strapped to the femur, thereby providing two surfacesangled at 45° from the longitudinal axis of the femur for guiding thechamfer cuts on opposing sides of the patient bone. In some embodiments,separate cutting guides 808 may be provided for the tibia and the femur.In some embodiments, the surgeon may select an advantageous order forperforming various cuts of one or more bones to reduce repositioning ofthe cutting guide 808.

In some embodiments, the bracket may include an adjustable ledge. Theadjustable ledge may allow for minor adjustments to the position of theledge with respect to the cutting plane without uncoupling the bracketfrom the patient anatomy. In some embodiments, a U-shaped bracket mayinclude a separate flat movable platform reversibly coupled to one orboth of the vertical portions of the bracket. For example, the verticalportions may include a plurality of holes and/or an extended slot forreceiving the platform and securing by a fastener at various heights onthe U-shaped bracket. In some embodiments, the movable platform may alsobe configured to be positioned at an angle, e.g., for guiding chamfercuts on a femur. In some embodiments, a movable platform may be providedon an L-shaped bracket with minor modifications.

FIG. 14 is a block diagram of an example data processing system 1400 inwhich aspects of the illustrative embodiments are implemented. Dataprocessing system 1400 is an example of a computer, such as a server orclient, in which computer usable code or instructions implementing theprocess for illustrative embodiments of the present invention arelocated. In one embodiment, FIG. 14 may represent a server computingdevice.

In the depicted example, data processing system 1400 can employ a hubarchitecture including a north bridge and memory controller hub (NB/MCH)1401 and south bridge and input/output (I/O) controller hub (SB/ICH)1402. Processing unit 1403, main memory 1404, and graphics processor1405 can be connected to the NB/MCH 1401. Graphics processor 1405 can beconnected to the NB/MCH 1401 through, for example, an acceleratedgraphics port (AGP).

In the depicted example, a network adapter 1406 connects to the SB/ICH1402. An audio adapter 1407, keyboard and mouse adapter 1408, modem1409, read only memory (ROM) 1410, hard disk drive (HDD) 1411, opticaldrive (e.g., CD or DVD) 1412, universal serial bus (USB) ports and othercommunication ports 1413, and PCI/PCIe devices 1414 may connect to theSB/ICH 1402 through bus system 1416. PCI/PCIe devices 1414 may includeEthernet adapters, add-in cards, and PC cards for notebook computers.ROM 1410 may be, for example, a flash basic input/output system (BIOS).The HDD 1411 and optical drive 1412 can use an integrated driveelectronics (IDE) or serial advanced technology attachment (SATA)interface. A super I/O (SIO) device 1415 can be connected to the SB/ICH1402.

An operating system can run on processing unit 1403. The operatingsystem can coordinate and provide control of various components withinthe data processing system 1400. As a client, the operating system canbe a commercially available operating system. An object-orientedprogramming system, such as the Java™ programming system, may run inconjunction with the operating system and provide calls to the operatingsystem from the object-oriented programs or applications executing onthe data processing system 1400. As a server, the data processing system1400 can be an IBM® eServer™ System p® running the Advanced InteractiveExecutive operating system or the Linux operating system. The dataprocessing system 1400 can be a symmetric multiprocessor (SMP) systemthat can include a plurality of processors in the processing unit 1403.Alternatively, a single processor system may be employed.

Instructions for the operating system, the object-oriented programmingsystem, and applications or programs are located on storage devices,such as the HDD 1411, and are loaded into the main memory 1404 forexecution by the processing unit 1403. The processes for embodimentsdescribed herein can be performed by the processing unit 1403 usingcomputer usable program code, which can be located in a memory such as,for example, main memory 1404, ROM 1410, or in one or more peripheraldevices.

A bus system 1416 can be comprised of one or more busses. The bus system1416 can be implemented using any type of communication fabric orarchitecture that can provide for a transfer of data between differentcomponents or devices attached to the fabric or architecture. Acommunication unit such as the modem 1409 or the network adapter 1406can include one or more devices that can be used to transmit and receivedata.

Those of ordinary skill in the art will appreciate that the hardwaredepicted in FIG. 14 may vary depending on the implementation. Otherinternal hardware or peripheral devices, such as flash memory,equivalent non-volatile memory, or optical disk drives may be used inaddition to or in place of the hardware depicted. Moreover, the dataprocessing system 1400 can take the form of any of a number of differentdata processing systems, including but not limited to, client computingdevices, server computing devices, tablet computers, laptop computers,telephone or other communication devices, personal digital assistants,and the like. Essentially, data processing system 1400 can be any knownor later developed data processing system without architecturallimitation.

In the above detailed description, reference is made to the accompanyingdrawings, which form a part hereof. In the drawings, similar symbolstypically identify similar components, unless context dictatesotherwise. The illustrative embodiments described in the detaileddescription, drawings, and claims are not meant to be limiting. Otherembodiments may be used, and other changes may be made, withoutdeparting from the spirit or scope of the subject matter presentedherein. It will be readily understood that the aspects of the presentdisclosure, as generally described herein, and illustrated in theFigures, can be arranged, substituted, combined, separated, and designedin a wide variety of different configurations, all of which areexplicitly contemplated herein.

The present disclosure is not to be limited in terms of the particularembodiments described in this application, which are intended asillustrations of various aspects. Many modifications and variations canbe made without departing from its spirit and scope, as will be apparentto those skilled in the art. Functionally equivalent methods andapparatuses within the scope of the disclosure, in addition to thoseenumerated herein, will be apparent to those skilled in the art from theforegoing descriptions. Such modifications and variations are intendedto fall within the scope of the appended claims. The present disclosureis to be limited only by the terms of the appended claims, along withthe full scope of equivalents to which such claims are entitled. It isto be understood that this disclosure is not limited to particularmethods, reagents, compounds, compositions or biological systems, whichcan, of course, vary. It is also to be understood that the terminologyused herein is for the purpose of describing particular embodiments onlyand is not intended to be limiting.

With respect to the use of substantially any plural and/or singularterms herein, those having skill in the art can translate from theplural to the singular and/or from the singular to the plural as isappropriate to the context and/or application. The varioussingular/plural permutations may be expressly set forth herein for sakeof clarity.

It will be understood by those within the art that, in general, termsused herein, and especially in the appended claims (for example, bodiesof the appended claims) are generally intended as “open” terms (forexample, the term “including” should be interpreted as “including butnot limited to,” the term “having” should be interpreted as “having atleast,” the term “includes” should be interpreted as “includes but isnot limited to,” et cetera). While various compositions, methods, anddevices are described in terms of “comprising” various components orsteps (interpreted as meaning “including, but not limited to”), thecompositions, methods, and devices can also “consist essentially of” or“consist of” the various components and steps, and such terminologyshould be interpreted as defining essentially closed-member groups. Itwill be further understood by those within the art that if a specificnumber of an introduced claim recitation is intended, such an intentwill be explicitly recited in the claim, and in the absence of suchrecitation no such intent is present.

For example, as an aid to understanding, the following appended claimsmay contain usage of the introductory phrases “at least one” and “one ormore” to introduce claim recitations. However, the use of such phrasesshould not be construed to imply that the introduction of a claimrecitation by the indefinite articles “a” or “an” limits any particularclaim containing such introduced claim recitation to embodimentscontaining only one such recitation, even when the same claim includesthe introductory phrases “one or more” or “at least one” and indefinitearticles such as “a” or “an” (for example, “a” and/or “an” should beinterpreted to mean “at least one” or “one or more”); the same holdstrue for the use of definite articles used to introduce claimrecitations.

In addition, even if a specific number of an introduced claim recitationis explicitly recited, those skilled in the art will recognize that suchrecitation should be interpreted to mean at least the recited number(for example, the bare recitation of “two recitations,” without othermodifiers, means at least two recitations, or two or more recitations).Furthermore, in those instances where a convention analogous to “atleast one of A, B, and C, et cetera” is used, in general such aconstruction is intended in the sense one having skill in the art wouldunderstand the convention (for example, “a system having at least one ofA, B, and C” would include but not be limited to systems that have Aalone, B alone, C alone, A and B together, A and C together, B and Ctogether, and/or A, B, and C together, et cetera). In those instanceswhere a convention analogous to “at least one of A, B, or C, et cetera”is used, in general such a construction is intended in the sense onehaving skill in the art would understand the convention (for example, “asystem having at least one of A, B, or C” would include but not belimited to systems that have A alone, B alone, C alone, A and Btogether, A and C together, B and C together, and/or A, B, and Ctogether, et cetera). It will be further understood by those within theart that virtually any disjunctive word and/or phrase presenting two ormore alternative terms, whether in the description, claims, or drawings,should be understood to contemplate the possibilities of including oneof the terms, either of the terms, or both terms. For example, thephrase “A or B” will be understood to include the possibilities of “A”or “B” or “A and B.”

In addition, where features or aspects of the disclosure are describedin terms of Markush groups, those skilled in the art will recognize thatthe disclosure is also thereby described in terms of any individualmember or subgroup of members of the Markush group.

As will be understood by one skilled in the art, for any and allpurposes, such as in terms of providing a written description, allranges disclosed herein also encompass any and all possible subrangesand combinations of subranges thereof. Any listed range can be easilyrecognized as sufficiently describing and enabling the same range beingbroken down into at least equal halves, thirds, quarters, fifths,tenths, et cetera. As a non-limiting example, each range discussedherein can be readily broken down into a lower third, middle third andupper third, et cetera. As will also be understood by one skilled in theart all language such as “up to,” “at least,” and the like include thenumber recited and refer to ranges that can be subsequently broken downinto subranges as discussed above. Finally, as will be understood by oneskilled in the art, a range includes each individual member. Thus, forexample, a group having 1-3 cells refers to groups having 1, 2, or 3cells. Similarly, a group having 1-5 cells refers to groups having 1, 2,3, 4, or 5 cells, and so forth.

Various of the above-disclosed and other features and functions, oralternatives thereof, may be combined into many other different systemsor applications. Various presently unforeseen or unanticipatedalternatives, modifications, variations or improvements therein may besubsequently made by those skilled in the art, each of which is alsointended to be encompassed by the disclosed embodiments.

1. A system for resecting a bone of a patient, the system comprising: arotary tool having: a tool body, a tracking array affixed to the toolbody, the tracking array comprising three or more fiducial markers, apowered rotary cutting tip comprising a longitudinal axis, wherein thepowered rotary cutting tip is affixed to the tool body and rotatableabout the longitudinal axis by a motor to resect the bone, first andsecond linear actuators configured to adjust one or more of a verticalposition and a pitch position of the powered rotary cutting tip withrespect to the tool body, and a tool rest extending from the tool bodyconfigured to maintain contact with the bone as the tool body is movedto resect the bone; a surgical tracking device configured to identify aposition of each of the three or more fiducial markers with respect tothe bone; and a processor configured to cause the system to: receive asurgical plan comprising at least one virtual cutting plane on the bone,receive the position of the three or more fiducial markers from thesurgical tracking device, determine, based on the position of the threeor more fiducial markers, a real-time pose of the cutting tip withrespect to the at least one virtual cutting plane, and control the firstand second linear actuators, based on the real-time pose, to adjust oneor more of the vertical position and the pitch position of the rotarycutting tip with respect to the tool body to maintain the powered rotarycutting tip on the at least one virtual cutting plane.
 2. The system ofclaim 1, wherein the powered rotary cutting tip has a fixed horizontalposition and a fixed axial position with respect to the tool body. 3.The system of claim 1, wherein the powered rotary cutting tip has afixed yaw position with respect to the tool body.
 4. The system of claim1, wherein the processor is configured to prevent the powered rotarycutting tip from cutting across the at least one virtual cutting plane.5. The system of claim 1, wherein the at least one virtual cutting planecomprises a vertical cutting plane and a horizontal cutting plane. 6.The system of claim 5, wherein the processor is further configured to:maintain the longitudinal axis of the powered rotary cutting tip on thevertical cutting plane when a movement axis of the first and secondlinear actuators is substantially orthogonal to the vertical cuttingplane; and maintain the longitudinal axis of the powered rotary cuttingtip on the horizontal cutting plane when the movement axis of the firstand second linear actuators is substantially orthogonal to thehorizontal cutting plane.
 7. The system of claim 5, wherein the toolrest is further configured to: pivot about a fixed point on a contactsurface with the bone during movement of the powered rotary cutting tipalong the vertical cutting plane; and move along the contact surface ofthe bone during movement of the powered rotary cutting tip along thehorizontal cutting plane.
 8. The system of claim 1, wherein theprocessor is further configured to control a speed of rotation of thepowered rotary cutting tip about the longitudinal axis to resect thebone.
 9. The system of claim 8, wherein the processor is furtherconfigured to stop rotation of the powered rotary cutting tip when therotary cutting tip intersects the at least one virtual cutting plane.10. The system of claim 8, wherein the processor is further configuredto stop rotation of the powered rotary cutting tip when the rotarycutting tip is moved outside of a prescribed cutting area.
 11. Thesystem of claim 1, wherein each of the first and second linear actuatorscomprises one or more of a linear motor, a piezoelectric motor, apneumatic motor, a hydraulic motor, and a gear motor.
 12. The system ofclaim 1, wherein the tool rest is rotatable with respect to the toolbody.
 13. The system of claim 1, wherein the processor is furtherconfigured to control a position of a robotic arm to which the rotarytool is affixed.
 14. A rotary tool for resecting a bone of a patient,the rotary cutting tool comprising: a tool body; a tracking arrayaffixed to a tool body, the tracking array comprising one or morefiducial markers configured to be tracked by a surgical tracking system;a powered rotary cutting tip comprising a longitudinal axis, wherein thepowered rotary cutting tip is affixed to the tool body and rotatableabout the longitudinal axis by a motor to resect the bone of thepatient; first and second linear actuators configured to be actuated toadjust one or more of a vertical position and a pitch position of thepowered rotary cutting tip with respect to the tool body to maintain thepowered rotary cutting tip on the at least one virtual cutting plane;and a tool rest extending from the tool body and configured to maintaincontact with the bone as the tool body is moved to resect the bone. 15.The rotary tool of claim 14, wherein the powered rotary cutting tip hasa fixed horizontal position and a fixed axial position with respect tothe tool body.
 16. The rotary tool of claim 14, wherein the poweredrotary cutting tip has a fixed yaw position with respect to the toolbody.
 17. The rotary tool of claim 14, wherein each of the first andsecond linear actuators comprises one or more of a linear motor, apiezoelectric motor, a pneumatic motor, a hydraulic motor, and a gearmotor.
 18. The rotary tool of claim 14, wherein the tool rest isrotatable with respect to the tool body.
 19. (canceled)
 20. The rotarytool of claim 14, wherein the tool rest is further configured to: pivotabout a fixed point on a contact surface with the bone during movementof the powered rotary cutting tip along a vertical cutting plane; andmove along the contact surface of the bone during movement of thepowered rotary cutting tip along a horizontal cutting plane.
 21. Asystem for resecting a bone of a patient, the system comprising: arotary tool having: a tool body, a tracking array affixed to the toolbody, the tracking array comprising three or more fiducial markers, apowered rotary cutting tip comprising a longitudinal axis, wherein thepowered rotary cutting tip is affixed to the tool body and rotatableabout the longitudinal axis by a motor to resect the bone, first andsecond linear actuators configured to adjust one or more of a verticalposition and a pitch position of the powered rotary cutting tip withrespect to the tool body, and a tool rest extending from the tool bodyconfigured to maintain contact with the bone as the tool body is movedto resect the bone; a surgical tracking device configured to identify aposition of each of the three or more fiducial markers with respect tothe bone; a processor; and a non-transitory, computer-readable mediumstoring instructions that, when executed, cause the system to: receive asurgical plan comprising at least one virtual cutting plane on the bone,receive the position of the three or more fiducial markers from thesurgical tracking device, determine, based on the position of the threeor more fiducial markers, a real-time pose of the cutting tip withrespect to the at least one virtual cutting plane, and control the firstand second linear actuators, based on the real-time pose, to adjust oneor more of the vertical position and the pitch position of the rotarycutting tip with respect to the tool body to maintain the powered rotarycutting tip on the at least one virtual cutting plane.